The commentary you provided was embarrassingly wrong. I didn't want to go there, but here we are since you say so. For starters, it completely ignored the fact that Acts 13:33 says that Psalm 2:7 was fulfilled by Jesus being resurrected. I can understand why the commentary you provided would want to run away fast from it because it debunks the idea that Jesus played any part in his own resurrection and that Jesus and God aren't the same person. It also proves that Jesus wasn't always the Son of God.
Here's a Trinitarian who disagrees with you:
Barnes' Notes on the Bible
"This day have I begotten thee - It is evident that Paul uses the expression here as implying that the Lord Jesus is called the Son of God because he raised him up from the dead, and that he means to imply that it was for this reason that he is so called. This interpretation of an inspired apostle fixes the meaning of this passage in the psalm, and proves that it is not there used with reference to the doctrine of eternal generation, or to his incarnation, but that he is called his Son because he was raised from the dead. And this interpretation accords with the scope of the psalm. In
Acts 13:1-3 the psalmist records the combination of the rulers of the earth against the Messiah, and their efforts to cast off his reign. This was done, and the Messiah was rejected. All this pertains, not to his previous existence, but to the Messiah on the earth. In
Acts 13:4-5, the psalmist shows that their efforts would not be successful; that God would laugh at their designs; that is, that their plans should not succeed."