What I usually do, until something else comes up that may work, is place a post in the Char tab on day 1. That way I can update it with a bit of a roster for who is currently active and maybe some other important details. Granted that only works on new RPs.

I do agree that there can be an issue with giving GMs a bit of power with post management and accidentally doing some weird things. I know a hide post feature could be implemented, but you're still playing around with other people's post's.