Just like some muslims become radicalized groupthink zombies; the same goes for the antifa radicalized goons. All cut from the same cloth on similar missions. True, at the moment ISIS is more violent, at the moment. I think we all know how fast that can change. Just look at how this radicalized goon used a weapon (bike lock) to inflict a lot of damage quickly and violently.
It should be perfectly legal to blow someone like that away in every state nationwide for such a crime during a protest turned riot.
In most of the western states, this world be considered “intent to commit bodily harm” and you are within your legal rights to put a couple of rounds (or more) in his sorry ass.