Because Voldemort isn't real, and Tom was tired of the game anyway when he learned he should probably focus on Harry. (If he died, and was inconvenienced the way Dumbledore thinks, how did someone consistently sabotage the Defense Professor? Though that's weak evidence for a couple reasons.)
Dumbledore doesn't realize that Voldemort is a mask, otherwise he'd be spamming this news everywhere. Even without understanding it, he gave Harry a big hint by faking the scene with the burnt chicken. He hoped Harry would think it through and arrive at the same conclusion. But Albus doesn't want to say it explicitly because it would sound silly, and he already looks like a lunatic.
...I've never so much as heard the implication that Voldemort was actively sabotaging the Defense position so much as he cursed it once, and it is the curse that is continuing to do its work. Such speculation doesn't appear to make sense to me now that I have heard it.
Linking the burnt chicken to the burnt husk of Voldemort's supposed body, however...is not something that I've considered, and it actually makes some sense, though I do not say that with a high degree of certainty. Though, why wouldn't he have spoken up by now?
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 90. The previous thread has passed 750 comments.
There is now 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.)
The first 5 discussion threads are on the main page under the harry_potter tag. Threads 6 and on (including this one) are in the discussion section using its separate tag system. Also: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17,18,19.
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: