They are consumers not citizens in the eyes of United Airlines, and core concept of the rigid and heirarchical consumer producer relationship is "caveat emptor". The consumer - producer relationship furthermore is entirely undemocratic in character and will always remain so.
For a generation now, our status as citizens has been overtly degraded into mere consumerism in both the public and private spheres, it colonizes political rights and obligations and even degrades our political discourse (expl "Brand Romney") to an appalling degree. I take the Radical Jeffersonian View that "inalienable rights" take precedence in all relationships, they must be respected when one is voting, buying an airline ticket or being vetted as Cabinet Secretary. Granted this is a retrograde notion with heavy tinges of William Jennings Bryan to it, but without this most necessary Jeffersonian infusion aggreived passengers on our airlines can look forward summary execution if they don't obey an officer's orders.
Just remember, we didn't get to this pretty pass because the Institutions are so Powerful, Irresistible and Corrupt, we let them do it, OUR PASSIVITY ALONE incited them to degrade us all to the status of cattle-with-credit-cards.
As far as I am concerned this passenger "stood his ground" he wasn't armed and he doesn't have a million wingnuts at his back, but he was asserting himself as a citizen while the airline simply treated him like a consumer with all the abuse and violence that entails.