Free will is necessary for the existence of free choices. We cannot freely choose the good without the freedom to choose evil. If we did not have the ability to freely choose, it would be meaningless to ascribe morality to them. I feel like I'm repeating myself. Did you read the third paragraph of my post? If so, what exactly doesn't make sense about it? Or do you not believe in the existence of free will?
RE: Interventionism and the Problem of Evil