They're the ones with the guns, the handcuffs, or at least the authority to throw you off the train. They'll think of something.
A couple of things to say if approached by a police officer or other personnel if they threaten arrest:
"What am I being arrested for?"
"What are you going to charge me with?"
That last one makes it very difficult to arrest someone, when they have nothing to charge someone with.
Never said you should be impolite or disrespectful. And even if you made it the jail, it would never hold up in court. Stand your ground.