I agree that Aaron is really no better than the other members of the Qover but even though he's clearly retarded, he's still the "best" of the bad bunch which skews people's view of him in a more positive direction. I won't lie I did give some "points" to him for the Ralph fight challenge, but obviously that will never excuse his actions and inactions whilst part of the Qover.
Best thing he can do at this point to get any semblance of "redemption" is sing like a songbird to authorities about everything and be willing to testify in court. At least we know he'll dress appropriately (unlike Nick and Co.).
Yeah, he's just enacting revenge on the man who "led his wife on" or whatever shit Aaron said the Nicker said.