Fair enough, but please understand that the violence has absolutely nothing to do with the moron and is entirely the problem of the assailant.
It DOES have something to do with the moron. The only way it could be "entirely the problem of the assailant" is if the assailant got violent for absolutely no reason whatsoever, without anything even have occured before.
No, the moron angers and, in this case, specifically WANTS a fight and therefore he is the one who led the assailant to become violent. In my opinion, both should be charged.