There's a story in "Aikido and the New Warrior", compiled by Richard Strozzi Heckler, that addresses this very thing. Basically it goes like this:
A young guy is on a train in Japan, there is an obnoxious type who is hassling people. The young guy believes that this is the time for him to test his Aikido skills and prepares to counter the guy. This little old gentleman (aren't they all little old gentlemen?) shouts some innocuous comment and gets the guys attention. He then starts talking to him and within a short period they are conversing and the obnoxious guy is crying and pouring out his heart.
The young guy realises that this is the ultimate expression of aiki and everyone lives happily ever after.
Ok, I may have paraphrased a bit! But the moral still stands, there is almost always a non-violent answer to any solution, the simplest in your scenario would be to get up and move to another carriage. You could appologise and offer the guy a mint, start up a conversation, act crazy or just exude an aura of passive, non threatening, calmness. This last has worked for me on numerous occasions when working in 5 star resort security.
Just some ideas.
Regards
Neil
Neil Hawkins
"The one thing that must be learnt but
cannot be taught is understanding"