Well, I mean, if both are telling the truth that means that Mafia has another framer. I doubt that's likely. If they do it's plausible they targeted Spin, as he's a strong town player and framing him gets us to doubt him... as shown.
Then again, claiming doctor and framing is basically the prototypical scum response to being copped. The ultimatum is a nice twist, but... if you think about it, really doesn't prove he's town. If he has a hand in the scumkill, he can simulate the effects of Doctor.
Then AGAIN, if we have vigs we have a kill that isn't tied to scum.
Which Spin notices. And is worried about, because two stacked kills beats one doctor. By pointing it out he emphasizes that it doesn't give us any information if he's vigshot, as if Spin is the doctor it'll break through and look the same as if Spin wasn't the doctor. (maybe vig claims right after?) In the same post he also says the only way he could not be doctor and Random lives is that another doctor tries to save him. He's ignoring the possibility that if he were scum, he'd just tell Mafia to not kill Random - which makes it look like that's exactly what he's doing.
Also,
can anyone tell me whether Spin tends to play a strategy that involves claiming when he gets doctor, and if so, can Spin tell me what that strategy is?Oh, also... Spin, what's your full role name? I find it hard to believe that you're an unmodded doctor.
And once I'm wondering I notice that blueturtle's case analyses assume only one scum team: you left out possibilities in which two scum might be genuinely opposed and not working together. Unlikely, but still subtly incomplete as you yourself pointed toward as a sign of bias. Mind you, I think it's maybe a town bias so not all that bad for you.
They said the only alignments will be Town, Mafia, Mafia-ally, Cult, and Serial Killer. Random is specifically claiming Spin is Mafia, and can talk with an informed minority (the "dark cosmos"). The only way Spin is Cult, SK, or Mafia-ally is if Random was faking this all and just happened to land on another scum. That would be detectable in Spin's reaction, but Spin reacts in such a way to suggest a town (I'm the doctor, I can prove it) or a scum (Claim doctor then direct the scumkill off Random).