I strongly disagree about someone simply showing up to a violent protest with a gun being provocation.
Unless you're pointing it at people and/or threatening them with it, some exceptional individual has to see you with a gun and decide charging you like a bull is a great idea. If the gun is legal or not, that's essentially the same argument as "she deserved to be raped cause of how she was dressed", except in this situation the assailant was like 12 IQ and didn't realize the "dress" in this case could turn him into swiss cheese.
An assailant being a drooling mongoloid isn't an excuse for his assault.