Contained in Warb’s paranthetical is the idea that a gun safety lesson in a school can be legitimate but this guy shouldn’t be teaching it based on actions evincing recklessness. mfm takes the view that no such class is ever acceptable and/or any accident is proof of absurdity and incompetence.
I’m not sure whether a gun safety class is acceptable or not, but it is certainly not legitimate for a teacher to decide to do this on his own without the school’s knowledge or permission.