This does not follow, because in this scenario God would have willed evil. It would be better for you to say that God wills us a FREE WILL and in turn WE are the CAUSE of evil to exist in the world. The same goes for the fall of lucifer.
I worded my comment carefully in case you answered like this. By definition then, according to your comment, God willed to empower man to be able to thwart His will, thus making man MORE powerful than God on at least some issues. You would have to say that God lessened His sovereignty and control by transferring it to man in order that man have his freedom (to decide his own destiny, etc.). That's what I see all over Catholicism, frankly. God must be made lesser so that man (or a group of men) can be made greater.
God allows evil to exist but is not the author of it.
That is true, not because man decided it and God is forced to go along, it is true because that is how God willed it to be in the first place. From what I can tell of the Catholic position from your post (and others from Catholics), God said "Let man be free to do whatever he thinks is best and I will allow it." :)
Thanks for the Aquinas passage. I'm glad to see that he accepts and understands the concept of absolutes, and I agree with him that God knows what evil is and does not author it.
God humbled Himself so that we can be saved. God is not a control freak.