I'm not sure I want to get involved in your argument, but Ra's did not know that Batman's comrade (Gordon) was going to blow up the train tracks when he boarded the train. So I don't think it's correct to say that Ra's made a deliberate choice to board a train that was going to crash. Of course, any criminal endeavor (especially one involving a high-speed train and an extremely destructive microwave transmitter) involves some degree of risk, and R'as was probably aware that it was possible that he could die, but he probably thought the odds against him were insignificant. He had no idea how much danger he was really in.
Ra's did not even know that he would have to deal with Batman once he was aboard the train, because it was very uncertain that Batman would even be able to follow him after R'as ordered four of his assassins to attack Batman. In the comic books, Bruce Wayne could defeat any single one of them after he had completed R'as's training program (some of them he could just barely defeat), but beating four of them would be practically impossible. (Did you hear the tone in R'as's voice when he said, "As you wish"?) To the best of my knowledge, I don't think the comic books ever put Batman in that situation. (There are tons of comics, though, so I could be wrong.) The assassins normally worked alone, and originally, if they failed to kill their target, R'as punished them by killing them, so only the best survived. They're not your ordinary thugs. Not by a longshot. I wish the movie had shown more of that particular fight, because it was actually one of the most impressive things that Batman did.
That's the real reason why I responded to your message--so I could gush over that particular fight. But I bet R'as was very surprised to see Batman on the train.