I find it hard to believe that just seeing the gun was the only motivator. It is just odd.
The fact that he looks like this would be enough for some people.
I don't know if it really matters that CCW has been around so long. Those outside the loop aren't thinking about concealed guns, and aren't seeing them, either. They've never gotten used to what they weren't aware of.
The guy with the gun may, conceivably, have been acting strangely, but I think we've more chancing of finding that the "hero" is a bit of a nut. Probably some other stuff in his past.