I like this answer. Isreal has no problem with guns in schools and shopping malls Etc.
The startling thing is that the author of this piece is not wrong about the vast majority of teachers who would shoot themselves in the foot while wetting their pants it this were to happen in their school. They could be exempt from any requirement to have a weapon.
But there are a few teachers who would rather be armed and have a fighting chance at survival for themselves and their students. These are the only teachers who should be considered for training and arming.
You make a well reasoned comment. Having school staff armed is worthwhile in a deterrent aspect. Therefore, I support it. But to provide adequate defense from surprise attack requires something on the order of nuclear weapon etc. security arrangements.