Do these freaks really not remember what it was like to be a kid? Kids do crazy shit, it’s how we all learn about ourselves, our boundaries, our values. Punishing a kid for playing around like this will not help anyone, it will simply make it more likely that this kid acts out later because their sense of what’s socially acceptable and what’s not will be completely skewed by these absurd rules.
I played finger guns in school all the time (before active-shooter drills were a thing, to be fair), and it’s part of how I figured out that I hate guns and violence. Punishment first has never been effective, we need to trust ourselves and our kids a little more.