1 werewolf sleepwalker, 2 town sleepwalkers. I mean, it's possible. But it seems like a lot of sleepwalkers. the real question, though, is why would a non-sleepwalker wolf (i.e. Xam or Ultron) claim sleepwalker when they already knew there was an actual sleepwalker wolf (Terrabyte). That seems like a strange decision.
I disagree. The supposed doctor has no way of knowing who would get targeted yesterday, and there's a few reasons why he or she would not choose our Sheriff.
1. The Doctor thought Drop wouldn't be targeted, being so out in the open, so they picked someone else that they had a good read on.
2. The Doctor was afraid of a Wolf watcher would look into who targeted Drop last night, and, upon noticing that Drop wasn't killed, the wolves would have found the Doctor's identity.
3. The doctor was worried about someone else dying.
It's not that unreasonable. The Doctor knows just as we do that Drop's death passes on the baton to another villager, so the power isn't suddenly lost. It's a shame Drop died, but we still have the power of the double vote (assuming CrimsonFist is town). Protecting another villager with a suspected PR could be more logical choice, depending on the circumstances. So no, I don't think it's necessarily a bad play.