Hmm, the 10 minute limitation is around editing, as in we don’t want people to knee-jerk edit the post just to unhide it… but your proposal that a person on the receiving end of a flag (one that went to threshold, or a mod invoked it) not be able to reply to the topic for a bit is a very very interesting one!
This might have positive implications for spammers as well, and if it’s limited to the topic the flag was in, it shouldn’t be onerous.
