Quite why this is being discussed here, I’m not sure.
Anyway, an interesting perspective from Plastic787. Because the operating captain can’t make a pragmatic decision (ie his is the wrong one) he is petty, unmalleable (meaning you want to mould him) and can’t be trusted. So, you would get off, of course cancelling the flight you were rostered to do. Hmmm… Best you swap seats then as you appear to think you are the captain! In addition, I’m sure ops would be overjoyed by your rational decision process.
There may be many reasons why he may exercise his right to refuse a request. For example, as a long time trainer, I never took anyone on the flight deck that had no role to play in the training. This was purely for the benefit of the trainee to avoid any pressure or should things not go quite as planned. Despite a couple of complaints to Flt Ops, the answer was always the same; it is for the captain to decide.
Me