Are you saying that, once you are airside there is absolutely no way whatsoever to get back landside other than breaking the law and forcing your way illegally back through the border? And, if so, in what sense is this "reasonable"?
I can see the argument from both sides (hey, I am a lawyer, after all ) and I can see why both airlines and authorities do not want to encourage individuals to come back landside after having gone airside. I would, however, question the notion that it is reasonable to force all individuals to stay airside and get on their flight under any circumstances (other than, presumably, medical emergencies or irrops?) and not allow them landside even if their flight is, say 10 or 12 hours later.
Surely there is room for more reasonable solutions rather than absolute ones?