While a moderator isn’t around, watching like a hawk, this causes a two-part problem:
A user can do the bare minimum of editing by adding/removing a couple words to get his (completely unacceptable) post unhidden.
The users who flagged the comment, now can’t re-flag the slightly-edited comment because they flagged the original version and their “undo flag” option is now gone.
You may not have enough TL1+ users on a low-traffic topic to again hide the unacceptable comment, and it stays up (i.e. all weekend, with angry users responding) until an editor comes in to take a look.
I had a look at fixing that, and it’s tricky. The current code re-uses the logic for disagreeing with a flag, which prevents those people from flagging the same post again. I fix.
While @neil is working on this I wanted to add that a user who makes bad faith flagged post edits should almost certainly be suspended, or at the very least given a serious warning PM.