Dumbledore is a side character. He needed to be got rid of, so neither Harry nor the reader would expect or hope for Dumbledore to show up at the last minute and save the day
There's technically six more hours of story time for a time-turned Dumbledore to show up, before going on to get trapped. He does mention that he's in two places during the mirror scene.
Dumbledore has previously stated that trying to fake situations goes terribly wrong, so there could be some interesting play with that concept and him being trapped by the mirror.
Mirro!Dumbledore appears to not be time-turned: 110 was edited so that Dumbledore says:
"I am there," Albus Dumbledore said, "and also inside the Mirror, unfortunately for you. I have always been here, all along."
That doesn't sound like he just spun back - it sounds like there might be more than one Dumbledore running around.
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 112.
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: