Shove them in the holding cell and leave them to rot for the MassRDMers if there really is no staff on. I don't see any positive in giving PD a way to jail people for 20 mins. This can be easily abused and would just be generally bad for the crim player experience
Staff members can eject players from chairs. If we had the rule in place, people would still sit in the chairs AFK but the only difference is, is that they would receive a punishment for something so minor.