What meaning would Philippians 2:9 have if Jesus is equal with God? Was Jesus praised for not seizing equality with himself?

The text's central idea is that there is a fundamental difference between God's own perception of Himself, and of what it truly means to be divine, and (fallen) humanity's (mis)understanding of the same concept. Christ (correctly) embodied the former, rather than the latter, contrary to the (deeply deluded) expectations of his contemporaries, be they Jews or gentiles. Though godlike, Jesus does not grasp or reach for the same goals (lapsed) creation would otherwise (falsely) associate with the term.

Have this mind among yourselves, which is yours in Christ Jesus

Christ's humility (Matthew 11:29, 23:12; Luke 14:11, 18:14).

he was in the form of God

As Adam and Eve in paradise, before the fall, since man (John 19:5) was initially made in God's image (Genesis 1:26-27, 5:1; Wisdom 2:23); see also Last Adam and Adam Kadmon.

^{Typologically, the untilled ground from which Adam was taken (Genesis 2:4-7) parallels the untouched womb from which Christ was born (Matthew 1:18-25, Luke 1:26-36); notice also the Spirit's life-giving role and presence in both passages, as well as both being called sons of God (Luke 3:38).}

did not count equality with God a thing to be grasped

Unlike the primordial couple, whose hearts were poisoned by the venom of the snake, before grasping or reaching for the fruit of the tree of knowledge, in their perverted desire to become godlike (Genesis 3:1-6), in a manner befitting fallen angels (Isaiah 14:12-14).

emptied himself

Of man's ancestral pride and selfishness (Matthew 16:24, Mark 8:34, Luke 9:23).

by taking the form of a servant

As opposed to that of a master (Matthew 20:25-27, 23:11; Mark 10:42-44; Luke 22:25-27) or earthly king (Matthew 21:5, John 12:15), contrary to preconceived Jewish expectations of how the Messiah was supposed to be(have).

being born in the likeness of men. And being found in human form

Fallen humanity, when contrasted to its initial paradisiacal state, alluded to earlier (Psalm 82:6-7, Hebrews 4:15).

he humbled himself by becoming obedient to the point of death, even death on a cross

The crucifixion, seen as a harrowing self-sacrifice, in light of Christ's complete obedience (Matthew 6:10, 26:42; Luke 11:2, 22:42).

The key point is the phrase, "considered it not". In other words, it would not have been considered robbery for the Son to have grasped on to, to have retained, equality with God. The Son was not trying to steal something that only belonged to God. Quite the opposite. The Son let go of what was rightfully his (equality with God), and humbled himself to death on a cross, in order that God be glorified. For this, he was praised. He was not seeking his own glory as the Son, but seeking to glorify the Father. For this he was praised.

However, the question you ask, "Was Jesus praised for not seizing equality with himself?" shows misunderstanding of the concept of how the Son relates to the Father. It would be an absurd impossibility for the Son to have tried seizing something for himself that he already had!

The verses in question only make sense when, for a short time, the Son lets go of being in the form of God in order to add human nature to his divine nature. To let go entailed being born on earth to a human mother, from whom he obtained human nature. By agreeing for that to happen, Christ became the man, Jesus, limiting himself to human form. He could not retain his place in the invisible heavens but had to become visible in the flesh, as a baby who grew to manhood, remained sinless and suffered death on the cross, that he might be vindicated by the Father with resurrection. All of this brought glory to God, as the righteousness of God was demonstrated by what happened at Golgotha and the empty tomb.

A helpful version of the text is in Young's Literal Translation, which reads:

"For, let this mind be in you that [is] also in Christ Jesus, who, being in the form of God, thought [it] not robbery to be equal to God, but did empty himself, the form of a servant having taken, in the likeness of men having been made, and in fashion having been found as a man, he humbled himself, having become obedient unto death - death even of a cross, wherefore, also, God did highly exalt him, and gave to him a name that [is] above every name, that in the name of Jesus every knee may bow - of heavenlies, and earthlies, and what are under the earth - and every tongue may confess that Jesus Christ [is] Lord, to the glory of God the Father" (vss. 5-11).

You will note that I have quoted the entire sentence, and not just a part of it. When asking what one particular verse in the Bible means, the starting point has to be the whole sentence, and not just a bit of it. Now it becomes clear that what the Son did, in letting go of equality with the Father (for a season), brought glory to God the Father, and (unavoidably) glory to himself due to their shared, divine, nature. This is shown in the last book of the Bible where Christ being the light in the heavenly Jerusalem is equated with the glory of God:

"And I saw no temple thereon: for the Lord God Almighty and the Lamb are the temple of it. And the city had no need of the sun, neither of the moon, to shine in it: for the glory of God did lighten it, and the Lamb is the light thereof... And he shewed me a pure river of water of life, clear as crystal, proceeding out of the throne of God and of the Lamb... And there shall be no more curse: but the throne of God and of the Lamb shall be in it... for the Lord God giveth them light" (Rev. 21:22-22:5).

Conclusion: Jesus could not have been praised for trying to seize equality with himself - he could only have been praised for letting go of that which was his by right, in order to bring glory to the Father, the end result being the glory of Father and Son, in the Spirit, in the new heavens, the new Jerusalem above.