Unless one goes backwards through the checkpoint (WTMD and TDC), one usually has to go through the sterile area to get out of the checkpoint once in it. (Think DCA JuiceGate).
So I guess a TSO would have to escort someone out of the checkpoint into the sterile area and then to the exit of the sterile area in effect escorting them out of the sterile area.
Perhaps, but that seem problematic.
A prohibited item is introduced to the sterile area even if for only a short period of time. If the prohibited item as an explosive it could be detonated at that point.