Stealing a powerful wizard's wand, even if you yourself are invisible, isn't a small feat.
Harry has no way to reach Quirrel on his own. He doesn't even know where Draco or Snape are, and can't reach them either. He also can't bring in another student.
Dumbledore can't help him now (people would notice if he stepped out for a few seconds), so he'd have to rely on him going back in time later to help him - Harry can't manipulate the wands himself, let alone false memory charm someone. This has the usual problems of relying on something already being modified by future travel back in time, without actually observing it.
Harry can't know if Jugson has an alibi for that time.
Fair points, it would be very impressive if he could pull it all off, but I think Dark Harry could manage to do it with some luck.
*For the wand I was thinking of something like pulling it out and then pushing someone into Lord Jugson and dropping it at his feet. He could properly time it so that 1st harry pulls it out and runs then 2cd harry immediately pushes either Jugson or someone into Jugson and drops the wand at his feet. Even if Jugson suspects something what can he prove?
*If Quirrel had returned to the School already Harry would know, if he is...
EDIT: New discussion thread here.
This is a new thread to discuss Eliezer Yudkowsky's Harry Potter and the Methods of Rationality and anything related to it. With two chapters recently the previous thread has very quickly reached 500 comments. The latest chapter as of 17th March 2012 is Ch. 79.
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: one, two, three, four, five, six, seven, eight, nine, ten.
As a reminder, it's often useful to start your comment by indicating which chapter you are commenting on.
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: