It’s not about merely knowing someone, it’s about the fact that the mess of her life CAME TO THE SCHOOL intending violence. He got 2 felony charges for what happened there, and it only happened there because she was there. What if the guy comes again because she’s there and goes full Newtown? Who are you going to blame then? Who are you going to say should have done something different? If either of your answers include the school you just explained why they chose not to renew her contract. She has defined herself as a source of risk to the school and everyone in it.
I get that he came there, but do we not hire people because they have crazy relative? Where do we draw the line?