Are there any commentaries from Trinitarians that explain why the Holy Spirit doesn't have a throne/receive worship in Revelation?

The Holy Spirit seems to be the One who is responsible for the vision of Revelation and He is frequently seen throughout the book. John was in "the Spirit" when it opens and the "Spirit" was the One speaking to the 7 churches through the 7 letters in chapters 2-4. The Spirit speaks in 14:13. The Spirit carries John away in 17:3 and 21:10. Finally, the Spirit and the bride (the Church) offer the invitation to all to "come" to God in 22:17. Anytime communication (speech, vision, etc) takes place from God toward humans, it is through the Holy Spirit. Anytime we pray in the Spirit to the Father, the Holy Spirit delivers our message of prayer to God. He is the intermediary. Hope this helps.

You asked for answers from Trinitarians. This answer is informed by a combination of current Catholic teaching (the Catechism) and Scripture. Other Trinitarian denominations may have differing teachings to refer to. (And other Catholics may rely on other teachings, Scripture, and utterances to make a similar point).

1. Consider the role of the Holy Spirit. I'll use three citations in scripture (from John) that point to the Holy Spirit being sent to us for help while we are in the mortal realm. In the afterlife, per the point in Revelation that you raise, one is in the presence of the Father and the Son. The Holy Spirit's purpose has been completed, because whomever is in the presence of the Son in Heaven has achieved salvation -- which was the point of sending the Holy Spirit (Paraclete, helper) in the first place. (The RCC applies a definitional point in the Catechism, see bellow, regarding the Trinity: if one is in the presence of the Son in Heaven, one is by default in the presence of the Holy Spirit).

   • John 14:23-26

     23 Jesus answered and said to him, "Whoever loves me will keep my word, and my Father will love him, and we will come to him and make our dwelling with him.
     24 Whoever does not love me does not keep my words; yet the word you hear is > not mine but that of the Father who sent me.
     25 "I have told you this while I am with you.
     26 The Advocate, the holy Spirit that the Father will send in my name --he will teach you everything and remind you of all that (I) told you.

   • John 15:26-27

     26 "When the Advocate comes whom I will send you from the Father, the Spirit > of truth that proceeds from the Father, he will testify to me.
     27 And you also testify, because you have been with me from the beginning.

   • John 16:7-13

     7 But I tell you the truth, it is better for you that I go. For if I do not go, the Advocate will not come to you. But if I go, I will send him to you.
     8 And when he comes he will convict the world in regard to sin and righteousness and condemnation:
     9 sin, because they do not believe in me;
     10 righteousness, because I am going to the Father and you will no longer see me;
     11 condemnation, because the ruler of this world has been condemned.
     12 "I have much more to tell you, but you cannot bear it now.
     13 But when he comes, the Spirit of truth{Holy Spirit}, he will guide you to all truth. He will not speak on his own, but he will speak what he hears, and will declare to you the things that are coming.

   Jesus identified himself as "the way, the truth and the life." (John 4:16) The Holy Spirit guiding the mortal disciples to the truth points to his role in salvation: keeping people who are alive on earth heading in the right direction -- toward Jesus and hence salvation.

   CCC 683 "No one can say 'Jesus is Lord' except by the Holy Spirit." "God has sent the Spirit of his Son into our hearts, crying, 'Abba! Father!"' This knowledge of faith is possible only in the Holy Spirit: to be in touch with Christ, we must first have been touched by the Holy Spirit. He comes to meet us and kindles faith in us. By virtue of our Baptism, the first sacrament of the faith, the Holy Spirit in the Church communicates to us, intimately and personally, the life that originates in the Father and is offered to us in the Son.

2. The Holy Spirit helps the living achieve salvation. Then what? Once a person is no longer among the living (the scenes from Revelation in your question), the Catholic Church teaches that you are with God, you are with Christ, and you are with the Holy Trinity. (Per the first passage from John, above, the Holy Spirit has been with you all along. A sincere "thank you" to the Holy Spirit would be in order for helping you get there. ;) )

   CCC 1023 Those who die in God's grace and friendship and are perfectly purified live for ever with Christ. They are like God for ever, for they "see him as he is," face to face 1024 This perfect life with the Most Holy Trinity - this communion of life and love with the Trinity, with the Virgin Mary, the angels and all the blessed - is called "heaven." Heaven is the ultimate end and fulfillment of the deepest human longings, the state of supreme, definitive happiness.

   1025 To live in heaven is "to be with Christ."
   1026 By his death and Resurrection, Jesus Christ has "opened" heaven to us.

To sum up: the Holy Spirit is sent forth to help you get to Heaven. Once in Heaven, due to being part of the Trinity, the Holy spirit is still there with you even though the VIPs whom you've been on the journey to meeting in full -- the Father and the Son -- are more prominent in this stage of your life, aka eternal life. He's there, even though you don't "need" him any more.

From the Holy Spirit's perspective: mission accomplished.

The question is about the current role of the Holy Spirit.

As Barnes (and others) note [Commentary John 14] it was the plan for Jesus to return to heaven after his death and send the Holy Spirit to be with disciples forever. As Jesus said:

And I will ask the Father, and he will give you another Helper, to be with you forever (John 14:16 ESV)

Jamieson-Fausset-Brown Bible Commentary says:

The Spirit is here promised as One who would supply Christ's own place in His absence. That he may abide with you for ever—never go away, as Jesus was going to do in the body.

Jesus left. The Holy Spirit came and is present with believers on the earth. The current work of the Holy Spirit is not to reign or exercise His own authority; it is to testify about Jesus, convict the world concerning sin, righteousness and judgement:

But when the Helper comes, whom I will send to you from the Father, the Spirit of truth, who proceeds from the Father, he will bear witness about me. (John 15:26 ESV)

Nevertheless, I tell you the truth: it is to your advantage that I go away, for if I do not go away, the Helper will not come to you. But if I go, I will send him to you. And when he comes, he will convict the world concerning sin and righteousness and judgment: (John 16:7-8 ESV)

The absence of the Holy Spirit on a throne is explained by His current role. Also The Holy Spirit hears what is spoken from the throne and speaks what He heard to those on the earth:

When the Spirit of truth comes, he will guide you into all the truth, for he will not speak on his own authority, but whatever he hears he will speak, and he will declare to you the things that are to come. He will glorify me, for he will take what is mine and declare it to you. All that the Father has is mine; therefore I said that he will take what is mine and declare it to you. (John 16:13-15 ESV)

I see your question as two-fold. You are asking for a Trinitarian commentary explaining the absence of worship directed toward the Holy Spirit. I cannot answer about Trinitarian commentaries.

And your underlying question is, why are the worship scenes in Revelation directed only toward the Father and Son if the Holy Spirit is an equal member of the godhead? I commend you on your insight to recognize these as worship scenes.

The book of Revelation is the testimony of Jesus. (Rev. 1:2) This means it is His testimony, His story. Just as Paul gave the gospel message through his testimony--his experience--the book of Revelation is telling the experience of Jesus from His arrival in Heaven until the last battle is won and the last enemy is destroyed.

In Rev 4 we see the ongoing worship of the Father for His act of Creation. (4:11 “Thou art worthy, O Lord, to receive glory and honour and power: for thou hast created all things, and for thy pleasure they are and were created.) Contrast this worship scene with the change that is occurring in the throne room in Chapter 5.

Chapter 5 opens with the Ancient of Days holding a sealed scroll that no man can open. (5:1-4) But suddenly, One is found worthy to open this scroll. (5:5) The Lion of the Tribe of Judah is found worthy to open the scroll. And a worship scene follows. (5:9-10) In the worship scene we are told why He is worthy: Because You were slain; You have redeemed every person on earth by Your blood; and You have made us priests and kings unto God.

Then we are told the reward that He receives for His accomplishment (5:12). "You Are worthy to receive power, riches, wisdom, strength, honor, glory, blessing." This list omits the reward of a kingdom. Going forward into 6:1-2 we also see that He receives a crown, and taking the scroll, begins a quest. As Revelation continues, we can see one accomplishment after another, each time the worship in Heaven rising a note higher, praising Him for His accomplishments in the plan of Salvation.

Rev. 5;9-10 You were slain, redeemed us by Your blood, made us kings and priests unto God.

Rev. 7:10 (Salvation of the great multitude): Salvation to our God which sitteth upon the throne, and unto the Lamb. … Amen: Blessing, and glory, and wisdom, and thanksgiving, and honour, and power, and might, be unto our God for ever and ever. Amen.

Rev. 11:17 We give thee thanks, O Lord God Almighty, which art, and wast, and art to come; because thou hast taken to thee thy great power, and hast reigned.

Rev. 12:10 Now is come salvation, and strength, and the kingdom of our God, and the power of his Christ: for the accuser of our brethren is cast down, which accused them before our God day and night.

Rev. 15:3 Great and marvellous are thy works, Lord God Almighty; just and true are thy ways, thou King of saints.

Rev. 16:5, 7 Thou art righteous, O Lord, which art, and wast, and shalt be, because thou hast judged thus…. Lord God Almighty, true and righteous are thy judgments.

Rev. 19:1-2 Alleluia; salvation, and glory, and honour, and power, unto the Lord our God: For true and righteous are his judgments: for he hath judged the great who*e, which did corrupt the earth with her fornication, and hath avenged the blood of his servants at her hand.

Rev. 19:6-7 Alleluia: for the Lord God omnipotent reigneth. Let us be glad and rejoice, and give honour to him: for the marriage of the Lamb is come, and his wife hath made herself ready.

These accomplishments are summarized in two other verses in Revelation: "He who sat on [the white horse] had a bow and a crown was given to Him and He went out conquering and to conquer." (Rev. 6:2) "Now I saw Heaven opened, and behold, a white horse, and He who sat upon him was called Faithful and True... and on His head were many crowns..." (Rev. 19:11-13) He begins conquering and He continues conquering until the last enemy is destroyed (1 Corinthians 15:25-26) and He is crowned with many crowns of victory.

So to answer your second question: We are not being shown any worship regarding the Holy Spirit because this is not the purpose of these glimpses into heaven here in Revelation. These are not just all-inclusive random worship events. The Heavenly Worship scenes are occurring at each accomplishment of Christ as He completes His work of Salvation. This work of Christ is being accomplished at the request of the Father, so He too is included in these worship scenes.

The visions in Revelation that you cited in support of your contention (“that the Holy Spirit is, for all intents and purposes, absent from the major points, events, and these visions held in Revelation…”) seemed to ignore two critically relevant points in Revelation. The first is 4:2-4 & 9-11. Before the Lamb stands in the centre of God's heavenly throne, we are told that "there were seven lamps of fire burning before the throne, which are the seven Spirits of God." Then the heavenly ones around God's throne fall down in worship of God. This means the seven-fold Spirit (appearing here as lamps of fire surrounding the throne) also receives that worship.

"The Holy Ghost, who dwelt among the children of Israel, now dwells within the ecclesia or church of God represented in Revelation 1:20 by the seven golden candlesticks. He also appears in his infinite divinity as the seven lamps of fire burning before the throne... He is the sevenfold Spirit - perfect in himself and in all his interior operations - sent forth into each of the seven churches, yet in a mystery abiding before the throne of God." (The Revelation of Christ, p.100, John Metcalfe, http://www.johnmetcalfepublishingtrust.co.uk/contact_us.htm )

The second is 5:6, about “the seven spirits of God” which are “the seven eyes of the Lamb", who is “the Lion of the tribe of Judah” – the glorified Jesus Christ at the centre of this one throne of God in heaven. This means that the Holy Spirit is also included in that scene of worship. Verse 6 is commented on by the Protestant and Trinitarian web-site below which details one possible interpretation of the phrase, ‘the seven spirits of God’:

“The first is that the seven spirits of God are symbolic of the Holy Spirit. The Bible, and especially the book of Revelation, uses the number 7 to refer to perfection and completion. If that is the meaning of the “seven” in the "seven spirits," then it is not referring to seven different spirits of God, but rather the perfect and complete Holy Spirit.” https://www.gotquestions.org/seven-spirits-God.html

This would mean, then, that when the Lamb is receiving the worship of those surrounding the throne of God in heaven, the Holy Spirit is also being worshipped, as the seven eyes of the Lamb are part of his Being. There is no need for a separate throne for the Holy Spirit as he is 'within' the Lamb, Jesus, looking out from his eyes, as it were.

Verses 13 to 14 state, “And every creature which is in heaven, and on the earth, and under the earth, and such as are in the sea, and all that are in them, heard I saying, ‘Blessing and honour and glory and power be unto him that sitteth upon the throne, and unto the Lamb for ever and ever’. And the four beasts said, ‘Amen.’ And the twenty-four elders fell down and worshipped him that liveth for ever and ever.”

Not only is the Father being worshipped, but also the Son (the Lamb) whose seven eyes are the seven-fold Spirit of God. There is the triune Godhead being worshipped on this one heavenly throne.

Further to the matter of the Bible supporting the idea of worshipping the Holy Spirit equally as is the Father and the Son, here is another quote from the same Trinitarian web-site:

“The question of whether we should worship the Holy Spirit is answered simply by determining whether the Spirit is God. If the Holy Spirit is God, then He can and should be worshiped. Scripture presents the Holy Spirit as not merely a “force” but as a Person. The Spirit is referred to in personal terms (John 15:26; 16:7–8, 13–14). He speaks (1 Timothy 4:1), He loves (Romans 15:30), He chooses (Acts 13:2), He teaches (John 14:26), and He guides (Acts 16:7). He can be lied to (Acts 5:3–4) and grieved (Ephesians 4:30). The Holy Spirit possesses the nature of deity—He shares the attributes of God. He is eternal (Hebrews 9:14). He is omnipresent (Psalm 139:7–10) and omniscient (1 Corinthians 2:10–11). He was involved in the creation of the world (Genesis 1:2). The Holy Spirit enjoys intimate association with both the Father and the Son (Matthew 28:19; John 14:16 …Since the Holy Spirit is God, and God is “worthy of praise” (Psalm 18:3), then the Spirit is worthy of worship. Jesus, the Son of God, received worship (Matthew 28:9), so it stands to reason that the Spirit of God would also receive worship. Philippians 3:3 tells us that believers “worship by the Spirit of God and glory in Christ Jesus.” There is one God who eternally exists in three Persons. When we worship God, we naturally worship all three members of the Godhead.” https://www.gotquestions.org/worship-Holy-Spirit.html

I submit these two quotes in support of Protestant, Trinitarian belief in the Holy Spirit being worshipped in Heaven, particularly as depicted in the book of Revelation. The one throne in heaven is the 'seat' of the Father, the Son and the Holy Spirit. It is worth noting, also, that Catholic views on the worship of the Holy Spirit would not clash with Protestant ones.