It is pretty bad the way it ended up, but slicc could be right.
The guy could have been running his mouth thinking it was OK. "Dodgers still suck. We won the WS." Etc. Some people don't take it too lightly. Being a 40 year old blue collar worker from the bay, family man, etc. he probably thought it was all laughs. I've been to plenty of events. I never talk shit to an opposing fan.
Then the people on the Giants side have a point too. From what the articles have said this guy was blind sided from behind. A couple mexicans hit him from behind, stomped him while he was down, then ran off. That's a bitch move too, and sorry to say but "cholos" are generally like that.
It's just a bad situation all around. The Dodger organization should make it up to the guy and his family.