There is an error in your analysis. There is no reason to start 6 hours ago, since the alternative is being able to go back 6 hours in the future. Either way, he has the same amount of time. If he finds out he needs to do something in the past, then he could go back. The only difference between researching first and going back first, is that if he researches first, he keeps the option of using the time turner to do something else. (e.g. Use 6 versions of him to do something in parallel at the same time).
When choosing between closing doors available to him and researching, the rationalist researches first.
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: