What is the expected reaction of a civil airliner pilot upon an invalid request from a fighter jet?
What do rules have to do with your hypothetical situation?  At that point the question is what a completely unarmed person, who is immediately responsible for the lives of other people (assuming there are passengers), should do when another person who clearly doesn't obey laws and has a deadly weapon demands something, and nobody else has the power to interfere.
It seems to me that the choices available to the civil pilot are to comply, to refuse, or to try some sort of trick.  A rational person at that moment would be completely concentrated on survival for the aviator and passengers, and wouldn't be concerned about rules.