I'm a couple of weeks behind here, so let's get something caught up.
The townspeople knew the Doctor wasn't the target of the cyborg.
Like I said, they were desperate to give up anybody calling himself a doctor. I know it's not the greatest explanation, but I can't think of another one that makes any sense at all.
But it seems Moffatt is taking the Doctor down a dark path that will not have a good ending.
I think I agree with you on this, but I'm not sure where the path is leading. Ultimately, it's leading to the Plains of Tranzalore, but I not only don't have a clue, I can't even speculate yet as to what it means.
Speaking of your theory with a story arc--what's with the flickering light bulbs so far? At the beginning of Asylum when Rory visited Amy at her photo shoot, the light bulbs on her dressing room mirror were flickering. At the beginning of Dinosaurs Rory and his dad are changing a light bulb. In Mercy, the light bulbs in the town flicker. I'm going to watch for flickering light bulbs in the next episode.
I think you're definitely on to something here. I don't remember whether there were any flickering bulbs in Power of Three, but there were in Angels Take Manhattan. The symbolism is hard to miss.
As I've noted before, I think Moffat is telling a long story, starting with The Eleventh Hour and ending on the Plains of Tranzalore. The Silence, the Doctor's dark path, the Doctor erasing himself from the Universe are all a part of it. When the question is asked, the Doctor will have completely erased himself from the Universe and nobody but him will be able to answer. Well, him and one other, the one that I suspect is behind using the Silence, who in turn used the Daleks, Cybermen, Sontarans, etc.
When it was announced that the Doctor was getting a new companion, Karen Gillan made a statement along the lines of, "when we're gone, I hope we stay gone." As much as I love Rory and Amy, I also hope that there's no contrived way that we see them with him again. When Rose was brought back in S4, it cut the heart out of what happened at the end of Doomsday. In fact, the less said about The Stolen Earth/Journey's End, the better. Those 2 episodes annoy me like no other.