Those that are most heavily armed don’t seem very polite, but a lot of people get shot.
Remember, we're talking about intent here. Whether you believe it's true has zero bearing, it's whether he may.
You don’t send security to an event without the intent of using it if needed.
Well, sure. But that's like when I put on my seatbelt when I get in the car: I'm not planning to crash into someone just taking the necessary precautions. I know it will be necessary as time approaches infinity, but this is a far cry from saying I intend to get into an accident because I put my seatbelt on, which is effectively what we're talking about.
If your argument is that he's guilty because he knew he might have to use a gun to protect himself, rather than going with the intent of actually shooting someone, then I disagree that this even remotely makes him guilty of a crime, as this would mean I'm guilty of intending to cause an accident because I put my seatbelt.