I don't know why you try reasoning with somebody that gave negative trust feedback with child abuse and mental illness allegations.
He probably lives already in his imaginary world, where he can still scare somebody and where somebody still believes him.
You are right. To be honestly.. i don't know either.
I try to always call upon common sense and logic.
But i guess some people either don't want to or can't follow some simple logic

I think someone with a good mental health wouldn't behave as he does, so it indeed should be better to simply ignore him.