According to Catholic scholars, why did Jesus relate His ensuing Passion and Glorification to the visit of the Greek?

For questions of this sort, I like to go to the Catena application (iOS and Android versions are available). Of verse 23 (go into Catena and click on the verse to view commentaries), Cornelius a Lapide says (emphasis mine):

But Jesus answered them, &c. Do not drive away the Gentiles from me, but bring them to me. What I said before was at the beginning of my preaching, which was intended for the Jews only; but now, when my preaching as well as my life is coming to an end, and the Jews reject my preaching, I will pass over to the Gentiles. For the hour is coming, when I shall be glorified, not only by the Jews, but also by the Gentiles, throughout the whole world; I shall be acknowledged, that Isaiah, as the Messiah and the Saviour, and worshipped and adored by means of your preaching in every place. Moreover, the glorification of Christ is the glorification of all Christians.

Likewise, Cyril of Alxendaria (emphasis mine):

Seeing therefore that Gentiles are hastening in eager desire to see Him and to turn towards Him, on this account He says: The hour is come. For near at hand was the time of His Passion, after which the calling of the Gentiles immediately followed. And He calls the time now present "the hour," with the intention of shewing that no other occasion can bring Him to the necessity of suffering, save only this season marked out by His own appointed limitations. For having done all things that were to lead men on to faith, and having preached the word of the kingdom of heaven, He now desires to pass onward to the very crowning point of His hope, namely to the destruction of death: and this could not otherwise be brought to pass, unless the Life underwent death for the sake of all men, that so in Him we all may live. For on this account also He speaks of Himself as glorified in His Death, and in suffering terrible things at the hands of the sinners who dishonour Him. Even though by the angels in heaven He had been glorified from everlasting, yet nevertheless His Cross was the beginning of His being glorified upon earth by the Gentiles as God. For after He had left to themselves the Jews who openly despised Him, He turned to the Gentiles and is glorified by them as God, being confidently expected to come again in the glory of the Father. And He declares not merely that the Word shall then be glorified, but, shewing that He Who is ineffably to be regarded as sharing in humanity no less than Deity is One Only Son, He uses the title "Son of man:" for He is One Son and One Christ, capable since His Incarnation of no separation of Nature; but ever remaining and ever regarded as God, although clothed in flesh. (From the Syriac.) [He is One Son and One Christ, capable since His Incarnation of no separation of Nature,] except so far as this, that we may say that we acknowledge separately the Nature of the Word and [the nature] of the flesh. And [we may say] that they are not the same in conception, for the one is of the Essence of God the Father, but the other had its root upon earth in the holy Virgin. Nevertheless there is only One Christ of the two, Who is not divided into a duality of Sons after the concourse of these Natures which have been mentioned, but remains and is regarded as in possession of the power of the Godhead, although clothed in Flesh.

And, Saint John Crysostom

What is, The hour has come? He had said, Go not into the way of the Gentiles, (thus cutting away all excuse of ignorance from the Jews,) and had restrained the disciples. When therefore the Jews continued disobedient, and the others desired to come to Him, Now, says He, it is time to proceed to My Passion, since all things are fulfilled. For if we were to continue to wait for those who are disobedient and not admit these who even desire to come, this would be unbefitting our tender care. Since then He was about to allow the disciples to go to the Gentiles after the Crucifixion, and beheld them springing on before, He said, It is time to proceed to the Cross. For He would not allow them to go sooner, that it might be for a testimony unto them. Until that by their deeds the Jews rejected Him, until they crucified Him, He said not, Go and make disciples of all nations Matthew 28:19, but, Go not into the way of the Gentiles Matthew 10:5, and, I am not sent but unto the lost sheep of the house of Israel Matt 15:24, and, It is not meet to take the children's bread and give it unto dogs. Matthew 15:26 But when they hated Him, and so hated as to kill Him, it was superfluous to persevere while they repulsed Him. For they refused Him, saying, We have no king but Caesar. John 19:15 So that at length He left them, when they had left Him...

The point here seems to be that the Jews despised Him and the Gentiles were coming to Him, and that He therefore knew it was time for His crucifixion, because He would not send the Apostles to the Gentiles until after the Resurrection.