I have been in this position and then I let my passengers off - after they were fed and watered (included in their ticket price). Obviously I was told by jobsworth muppet that I was not allowed to do so. But people like this live to be ignored. As a crew we did our own handling (as there was no one else) but desperate times called for desperate measures.
But, ignoring common sense, can anyone tell me the real legal position? Can people be held an aircraft against their will? Can an airport make people stay on an aircraft? If someone insists on getting off (before the take-off roll), can you legally keep them on board?