Personally, I don't really see the point in having access to the powers. Just seems like a way for people to stop roleplay they don't like or let other players add to the story that 'wasn't intended' to happen. These things should be worked out in OOC threads, where it can usually be resolved to some extent, instead of using the heavy hand of editing posts or locking threads that's inherently unfair for the players involved. And if it can't be resolved, then staff should get involved and go about doing what being suggested, either locking threads or editing if necessary.
I do agree with Legix's suggestion that old threads (maybe 6+ months since last activity?) should get locked, though I think this could be fixed with timers, like how you can't edit posts after a while. I don't know whether that would work though, because I have no idea how the admin side of the site works.