Mefisto & Busyb
You said.....
"IF I see it as a genuine reason, then MY decision becomes that discretion will not be used."
Given that this thread is about the pilot group's reaction to an unpopular 3rd floor decision; what would your reaction be if you sensed* the other crew member's politely (but firmly) declining your invitation to extend his crew duty day was purely a "political" statement..... would that meet your criteria for a genuine reason or would you "shop the barsteward"....?
* sensed... because he is wise enough not state his reasons... he just says "cannot"... politely... but firmly....