Pretty common in every city in CA whenever their team wins/loses. I remember living in Alameda when the Raiders lost the Superbowl, going outside and listening to Oakland go nucking futs.
One; he can't do crap about it or he'll be in hot water from some very vocal people.
Two; he doesn't want to do anything about it, because burned cars and shattered windows look bad enough on TV. Add in some cracked heads and it looks worse.