The place had a protest planned and people with different political views came there. It’s not uncommon when you have a protest planned people travel. But as you say they attacked him assuming he was something he wasn’t. At that point he was within his right to defend himself m. It’s not like he can talk to them and they will shake hand and move on. People were emotionally charged from both sides and they wanted to beat the shit out of him and paid the priceYou know what, I understand your viewpoint. It’s very reasonable.
I think it may have been a horrendous misunderstanding. I think they thought he was an active shooter and decided to “take justice” but in fact he wasn’t one and thought they were attacking him.
Regardless, this guy had no business even being in the state let alone the protest or even the city it was held in.