If there's a disturbance which Dumbledore suspects is a distraction, why did he send only Snape, rather than several aurors/coming himself?
In canon, Dumbledore is called away for some business (Supreme Mugwump duties?), and I presume the same happens here. Now, why Dumbledore didn't time-turner to both be at that business and here is harder to say--unless Quirrel explicitly used the time-turner prevention on going back more than X hours to send a message to Dumbledore preventing him from using his time-turner? I didn't look closely enough at those rules to figure out whether or not it would be likely to work (and don't have the time to pull out the relevant bits of HPMOR).
One way of preventing Dumbledore from using a time-turner is to have the disturbance take place at Azkaban. And after Bellatrix's breakout, it shouldn't be difficult to have him consider another potential Death Eater escape as a matter of absolute emergency requiring his personal intervention.
Of course, Azkaban is the one place Quirrell can't act in directly, so he'd probably want to Imperius an off-duty Auror or something.
New chapter!
This is a new thread to discuss Eliezer Yudkowsky’s Harry Potter and the Methods of Rationality and anything related to it. This thread is intended for discussing chapter 104.
There is a site dedicated to the story at hpmor.com, which is now the place to go to find the authors notes and all sorts of other goodies. AdeleneDawner has kept an archive of Author’s Notes. (This goes up to the notes for chapter 76, and is now not updating. The authors notes from chapter 77 onwards are on hpmor.com.)
Spoiler Warning: this thread is full of spoilers. With few exceptions, spoilers for MOR and canon are fair game to post, without warning or rot13. More specifically: