Anthere:
If only because rules and habits are no more the same now that they were 3 years ago. There is an expectation that the candidate sysop knows the project quite well, know the people, know the rules..
...
I also think that if an editor away for 3 years just came back now... he would neither know the rules, nor be known himself by current editors.
I think it is completely fair to indicate on the list of administrators if an admin hasn't made edits for some months or even years. In fact, this is exactly what we're doing on
http://en.wikipedia.org/wiki/Wikipedia:List_of_administrators
This helps users to know whom they can contact for help and expect an answer.
However, revoking someone's status just because they *might* become active again without knowing the rules seems to violate the "Assume Good Faith" principle. If an admin pauses for 6 months and then goes back to performing admin operations, I expect them to make an effort to look at what's changed first. If they don't make such an effort themselves, again, it is not our duty to punish them, but to revert actions which have been made accidentally in violation of newly established rules, and to educate them.
Adminship is about trust. If we trust a person, we should know that they will try to do the right thing, even under changed circumstances. Therefore, we shouldn't have to take someone's privileges away just to make sure they don't do anything bad -- because this could indicate to them that we no longer *trust* them. I don't want to send this kind of message to people like Mintguy, Vicky Rosenzweig, April, Salsa Shark, Optim, Mirwin, Maximus Rex, or Zoe.
I believe this is especially true if an admin is still active on *Wikimedia*, but just not on the same project anymore.
Erik