To all those compelled to be stubborn:
Oh for GODS SAKES! So long as the jumpseater is in CASS or reciprocal and cleared, being polite, and acknowledging of your cockpit rules, GIVE THE GUY THE JUMPSEAT! It is that simple!
I know a few, and I mean, A FEW, captains that have some massive chip on their shoulder or insecurity issues (or any other personality flaw) that makes them HELL to fly with. I have seen these FEW guys deny a jumpseater because he was with a certain pilot group (that was obviously non-ALPA and/or non-union). Those FEW look so proud of their misplaced efficacy and are completely oblivious to the fact that the people they fly with are either laughing at them behind their backs and/or completely hated by the majority of the base and/or members of the pilot group they come in contact.
Here's a hint... if you want to evangelize ALPA, then invite the scorned jumpseater into the cockpit and have a meaningful and educating discussion with them! Oh yes, you also need to listen to their beliefs and opinions too, even if you think they are misplaced or without merit. All this of course if the jumpseater isn't being galactically stupid and rude.
What a pity that there are still individuals on the line who prescribe to the old world style of "if you don't agree with me, I will scorn you into submission". Kind of like the old style of religious conversion -- convert or you will die.
In summary, THERE ARE OTHER OPINIONS! LISTEN! Oh wait, you aren't listening anyway.
But if a hint is getting through, get off the high horse and don't start a jumpseat war, which you are most certainly doing even though you believe otherwise. Give a guy a ride to work, home, family event (emergency) so long as he/she is on CASS or a cleared reciprocal agreement. As Captain, you have the right to refuse jumpseat to someone you feel is not safe to be up there. SOMEONE YOU DISAGREE WITH IS NOT SOMEONE WHO IS UNSAFE TO BE IN YOUR COCKPIT! GEESH!