That's horrible, I hope you get somewhere with the letter. There is absolutely no reason to ban filming on a train. The only place they can ban filming is at a security checkpoint where films could help future terrorists/evil-doers avoid security. Two weeks ago when I was in the Bahamas I could film on planes and film in the airport, just not in customs.

You are right, that is a serious violation of basic freedom, and it was a very "communist" move by the railway.