Nice straw man.... Nobody on this forum has suggesting limiting captain’s authority on jumpseat access. Of course the captain ultimately decides if a jumpseater will be allowed. The adults here were just pointing out how inappropriate it would be to grant jumpseat access on the basis of vaccination status.

Similar to how it would be a nasty and unprofessional thing to do to turn away a jumpseater based on sexual preference, religion, etc.... that Captain should ultimately be counseled by his colleagues (jumpseat committee, CP, etc) about why its not acceptable.

At a previous airline there was a major safety concern observed by an FO and Jumpseater that led to a CA being called in for retraining. Afterwards the CA instituted a personal policy of no jumpseaters in the flight deck. Would you think this is an acceptable practice to allow at your airline?