I remember a newspaper item from years ago of someone being beaten up at Dodger Stadium for wearing another team’s colors—must have been the Giants’. Maybe that was an isolated incident. Watching MLB games I often see fans wearing the visiting team’s colors so it doesn’t seem to be a dangerous thing to do generally.
That happened in the parking lot after the game and the perpetrators were gang members. It was a fan dispute that turned violent. Dodger stadium doesn’t allow any tailgating of any kind anymore because of the threat L.A. gangs pose. That’s one very sad thing about going to a game there, but it’s just to try to keep people safe.