Yhea, that's not a workable approach. Seriously, Flamel is centuries old and has had the key to eternal life for all of that. and the largest hoard of lore on the planet for most of it. Trying to legilimency that mind has the most likely result of you becoming a drooling vegetable. Certainly, its not going to actually work. If it did, it would be point 1 on every single aspiring dark lords to-do list. That's actually my main reason for thinking "Not dead". A lot. Really, just a an absurd number, of people must have already tried this. It doesn't even matter what "It" is. Someone tried that one already. And failed. If Voldemort had attempted it in person? Maaaaybee. A hired hit? Nope.
I agree with your assessment of how powerful Perenelle/Flamel (side note: need a good portmanteau a la Quirrellmort) should be, having been able to outwit Baba Yaga in her sixth year and then having six hundred years of excellent leverage to accumulate lore and also maybe play with what the stone can do.
That objection notwithstanding, the most plausible non-Voldemort killer would be Bellatrix, using her superpower of very strict obedience to orders like "Just use AK and do not hesitate for any reason".
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 116.
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.)