Everybody thinks that the captain has broad authority to refuse jumpseaters.
Try it and see what happens.
ALPA's primary motivation, not to mention the carriers that actually own the seat, is to enable pilots to get to and from work.
Though ALPA supports the captain's authority they are more concerned that a pilot can get home or to work.
Just refuse a jumpseat and see wait for the ALPA response. These boards are filled with people talking about refusing jumpseats but I would bet that very few have actually done so.
The TSA has been pretty clear about the FFDO issue. Next time you fly with an FFDO ask him/her what they are told in training will happen if they are refused a jumpseat.
By the way Stilton, with respect to this quote;
"Whether someone is a working crewmember or jumpseater, however I advise them to 'cool it' with the gunplay.(No turning in your seat, posturing 'ready to draw' scaring the flight attendant when she brings me my tea !"
I can assure you that the FFDOs that you tell this to are just humoring you by not explaining to you that they don't really care about your opinion.
You do realize that should an incident occur in the cabin your FFDO FO has the authority to tell you where you are going to land your aircraft?