I know there aren't many if them about but what about a melty brain spinner with only one motor? Should that be counted out instantly because it only has one working motor? What if it was designed to have 2 motors working but one wasn't working, it may still work to some degree bit not be 'as' mobile.
A 2wd robot with one motor broke can still drive in a kinda straight line due to the momentum of the robot, if you kinda pulse it on and off forwards the momentum of the robot makes it go in a reasonably straight line. Skilled operators with vertical spinners can get the bot learning onto one wheel and so drive along in a straight line.
I think you should be able to put in the bot if you want to and it should not be counted as immobile unless it cannot move (ie. both motors are broken or it is flipped on its side etc.)