Well, at least he was being honest. That is mitigation in my book. I don't think he was crazy, I think he was just evil like the Las Vegas shooter. Unless he heard voices. I guess, you can tangentially say that he had sadistic personality disorder, anti social, psychopathic personality disorder or even egg shell BPD or something, and we as a society need to creatively innovate and figure out ways to help or stop them without big costs. It seems that people like this appear disconnected and there's always build up or a few moments in which threats could be stopped.