The thing is, it makes absolutely zero difference how many of the accidents happen. The “No True Scotsman” fallacy (if that’s the right one) in incredibly strong — a real trained teacher with a gun wouldn’t let this happen. It happened to that guy? Then he wasn’t a real trained teacher with a gun.
I accidentally saw a comment thread under a new article about the Georgian teacher who shot his gun. About half the people commenting referred to this idiot “liberal” with a gun. Because he didn’t act they way they wanted a teacher with a gun to act, he immediately became a “liberal,” and so not a real American with a gun.