Here's an idea:
There are plenty of regular, respected FReepers on the board in various timezones who have been posting for years. How about if the mods were able to give those members limited policing powers - such as being able to move posts to a temporarily banned area for mod review, or temporarily terminate posting privileges for a user, also subject to mod review.
It doesn't fix the problem, but it would help limit the damage that could be done by a troll. Perhaps these powers would only be actionable on posters who have been around (and active) for less than six months - every new member would then be considered conditional and subject to rapid editing by the "deputy mods".
The "real" mods could then check out the "deputy" pulls at their leisure, and reverse the decision if necessary.