Your desire to rewrite the scripture is not working except in your own mind.It is interesting that one would try to claim that this short, compact psalm creates a particularly defined category of people in the first verse and then renders them utterly irrelevant for the rest of the psalm. According to your interpretation, the verse could have been dropped and your interpretation of the Psalm would not be altered. Isn't that right? Is that what you think? God wrote something that wasn't needed. God gave us something superfluous?
Let us return to reality. Why do we think Paul quotes from this Psalm? Isn't it because Paul's own letter to the Romans speaks of these same fools in chapter 1? And doesn't Paul then turn this upon believers in chapter 2 who are doing the same thing, exchanging the truth for a faulty theology? Believers who choose to believe nonsense by exchange! So what then? Will those believers caught doing the same thing as the fool not also fall under judgement? Paul is giving us the answer to that question in chapter 3.
Your understanding is off at most every point, but you are happy with it.