I also think that this sets a very murky precedent. I don't disagree at all with banning AA if it turns out he has abused voting privileges, but so far there's no hard evidence that he did. Putting that aside for now, all we're left with is a block being based on whether some individual moderator "can tolerate" some controversial comment (meaning that it attracts both downvotes and upvotes, as far as the LW userbase is concerned). This strikes me as careless.