I just think that, based purely on what I read here, the man appears to be unwell and needs treatment.
What do you think his problem is (personality disorder, psychosis..?) and what sort of treatment do you think he needs?
On second thoughts, don't answer that. You don't know and I don't know. My general feeling is that he has shown a fairly longstanding pattern of unreasonable behaviour and I agree with you that prison is unlikely to change this. However, I would take a fair bit of convincing to believe that a psychiatric hospital would make a lot of difference, and it would be even more of a drain on public finances.