I agree with your sentiment, except in this case, the assassin appears to be more moderate than the victim, with regard to what he said. That's a puzzling and frightening thought!

The only motive we know of was stopping hatred. There's no manifesto, only some gamer memes engraved on bullet casings, which I suspect wasn't even done for this occasion. He was no bitter loner either. Which suggests that, in such a violent climate, anyone might suddenly think: "I don't like that guy, I'll take him out."