Locking / Finalizing Individual Comments

The site I'm working on right now requires users to be able to mark content as inappropriate. Right now I'm using the Flag module, and that seems to be working out really well. It's set up so that after X many users flagging a comment, the comment is unpublished and waits for a moderator to review it. The moderator can then delete, edit, re-publish, etc. the node as s/he sees fit.

Here's the catch: there's nothing I can find to stop the user from returning to the node and editing it back into something inappropriate. The Flag module's API also doesn't seem to provide an easy way to remove all the individual user flags at once, so that the users could re-flag the comment for un-publishing if this were to happen. I'm sure that I could wrangle the Flag module into resetting them all, but that's not really the ideal functionality. I would like to be able to lock a single comment after it's been moderated so that it cannot be edited anymore (except perhaps by other moderators). This ensures that a moderator only has to review a comment a single time.

Does anyone know of a module that allows the locking of comments, or anything close to the functionality I'm looking for? Have I overlooked something simple somewhere? If I have to, I could make a module that could do this (I think), but I'm really not into starting that until I've exhausted all my other options.

Thanks in advance for any help. ^_^