If Quirrell is lying, then asking the question "Why not use the green stunner in other circumstances where Avadra Kevadra was used?" may lead to that lie being uncovered.
I admit I had not considered Inferius on the centaur. However, I rather suspect that Quirrell is priming Harry here; he does something (hitting a centaur with a green stunner) that looks evil, then demonstrates that it is less evil than it was. In the future, then, Harry will be more inclined to believe that Quirrell has done something less evil than it looks like he has done; he could, for example, use Avadra Kevadra on Dumbledore later (making it look like a green stunner to Harry) in circumstances where a green stunner would not be evil and then rely on Harry to prevent any immediate revenge against himself (long enough to portkey away at least).
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 99, 100, and 101. The previous thread is at nearly 500 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, 20, 21, 22, 23, 24, 25, 26, 27
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: