I saw your tags about the Undead Prophet being created by halperin and weston and I think something similar. I didn't think of him as being a fake prophet. I thought he believes what he says but he's living and probably a doctor. Because if Simon was the first to react to the drugs how could the undead prophet already be able to make the power surge/give Simon the messages when Simon's only just waking up?
Hi! I think your version is very plausible. It has to be someone with insight in what's happening in the Weston and Halperin's institute and it can't be any PDS sufferer because of reasons you enumerated. I spent a lot of time thinking about it (as I'm sure we all did) and I think that both doctors must be involved (because during the power surge both of them had to witness the Undead Prophet's apparition, it would be weird if only of them was involved and the other was left hanging like 'mate what the fuck just happened did you see that weird shit?').
And when it comes to believing or not in the message they are sending - it is probable that someone who stands behind the Undead Prophet believes they are right and everythin goes as in Book of Revelations and they want to lead and inspire the undead.
But I have this weird feeling that all of it might be some big experiment made up by doctors or even the state (we remember that MP came to supervise how the resocialisation of the undead was going, he was there to "manage the problem") to make it easier to control the PDS sufferers. But it's only my speculation and I love conspiracy theories, so I might be overthinking it all.