"I won't go and you can't make me!"

NASA has decided that they won't repair damage to the space shuttle Endeavour's heat shielding tiles before it returns to Earth next week. Hearing that made me wonder what NASA might do if one of the crew were to decide that they won't come back to Earth on the shuttle because of that damage. After all the shuttle is docked to the International Space Station. Would they attempt to force the person onto the shuttle? Let them stay on the ISS until its next scheduled crew change, which would no doubt have to be moved up because of the extra supplies another resident on the ISS would use up? Certainly they hope that such a scenario never happens given the kind of troubles they've been having of late, troubles that have brought a lot of negative attention to the agency.