So if I support McCain (god forbid), and the conductor really likes holding his job, he could toss me off the train, and Amtrak would back him?
I don't know. All I know is that, in the FRA's eyes, the Conductor can do what he darn well pleases. It's his train, just like the PIC (pilot in command) can do whatever he darn well pleases on his plane. If a passenger sues or complains, the company might look into the matter and take disciplinary action, but traditionally, and I believe legally, yes.
But I'm not an expert (I resigned before being promoted to Conductor and working any passenger trains). Someone here probably knows more.
I don't know that Amtrak would back him, especially if you could prove that was indeed the reason that you were tossed off the train, and not for some other reason. However, the simple fact remains that you would be calling Amtrak to file your formal complaint from the side of the road, a train station, or perhaps even a police station. The conductor has the power to put you off the train for any reason and if you refuse, then he/she can order the police to remove you and they can't refuse. Even if they think that it's rediculous and the guy is off his rocker, the police have to comply with his edict. The conductor is lord and master of the train. He has the power to marry you, and he has the power to throw you off the train.
He might loose his job later on, especially if he's had other complaints against him, but your trip would still be ruined.
There was an incident maybe 3 or 4 years ago where a conductor threw someone off the train because of the T-Shirt that he was wearing. I don't recall precisely what it said, but IIRC it was something on the vulgar side. I believe that more than a few passengers complained about the shirt, and again I think that the conductor gave him a chance to change it. But when he refused, the train stopped at a crossing and he was kicked off the train.
I actually find myself laughing sometimes when I read stories about local cops boarding freight trains to hand the crew a ticket for blocking the crossing in their local town. First, the local town have no legal authority to do so. But, secondly the cop is breaking Federal law if he steps onto that train without permission from the conductor. Yes, it's very unlikely that the conductor is going to radio for his company police or State or Federal, but he could and they could arrest the officer for boarding the train without permission. And that officer would loose in court if it went to trial. Again, it's unlikely that it would ever get that far, much less that he'd receive any major sentence, unless he committed some other act while on board.
But again the conductor has ultimate power over his train, any cargo on it, and anyone on it.