Haven't people made attempts at formulating a policy for de-sysopping before now, and been shot down in flames?
This is a bit like the content-committee discussion - I'm not sure how much of a problem there really is. When have we ever truly needed to desysop someone? Can anyone point to an example?
Admins, by and large, behave perfectly well. I would hope that the community is selecting those who are trustworthy to be admins, and that peer-pressure from the responsible majority will keep the odd rouge in line.
Dan