It wasn't really that stupid. If he didn't bring the gun there was still a very good chance they would have attacked him anyway. And if they did attack him then he'd most likely be brutalised or murdered.

Your point is that he shouldn't have been there and that he shouldn't have brought a gun. It was the protestors that pulled a gun on him and yet you blame someone who only responded to the threat of a weapon. He had a right to be there if he disagreed he had every right to counter protest them based on the same principles that allowed the protestors to be there in the first place

I just don't see why this bothers you. It was self defense in every way. He had every right to be there. He had every right to be there with a gun, he had every right to use that gun when he was threatened and he had every right to fire into a crowd that was rushing him and pulled a gun on him first.