I've mixed feelings about what is going on here.
I've been feeling a great sense of unease about putting a man on trial and being held to society's standards of normal and reasonable behaviour, if he is psychotic or in some other way psychiatrically unwell.
However, surely he would have had a psychiatric assessment to determine fitness for trial, because that wouldn't be fair for someone with a genuine mental illness? Or, do the reports come after, once he has been found guilty of committing the crimes?
The way I see it, there are two choices here - either he believes his fantasy or it is an act. The fact that he hopes the jury will believe something not humanly impossible but very close to impossible in terms of reasonable judgement, is delusional by most people's reckoning, I would say. On balance however, I think it is more likely to be a case of him being completely devious and trying out the only defence he can use - to see if he can raise reasonable doubt. I think we are seeing a manipulative and cunning act.
I think his OCD is going to muddy things when it comes to deciding if he is unstable in all respects, so as to be out of touch with reality.