None of what you suggested is a viable option when you are face to face with a deranged person
Of course it is. A possibly deranged person who isn’t violent, who hasn’t attacked, or even touched you. That’s no excuse to use lethal force. You’re not going to respond because you know you’ve lost the argument. When you admitted it was harassment you knew that it wasn’t suitable for killing, but you want to pretend that it is, because you like the idea of being able to kill someone who annoys you.