Originally Posted by Gotham's Knight
Ra's stabbed the controls himself, Batman didn't make him. Ra's made the choice to condemn himself to death.
But don't forget that prior to that, Batman told Gordon to blow the monorail supports to derail the train and also, "who said anything about stopping it". Ra's Al Ghul's face there is priceless by the way.
That's a little premeditated don't you think? Even if the controls weren't damaged in the brawl, Batman still intended to bring down the train with Ra's in it. It doesn't really bother me (I sort of dig Batman's slightly sadistic response to his unfaltering mentor) but I can see how Batman's cold little quip isn't too heroic for some people's tastes and that they'd be against it.
It might have been better for Batman to try and make an attempt to save Ra's for a second time, only to have Ra's refuse. Like I said, it's murky. For someone that's as good and noble as Batman, the whole "I won't kill you, but I don't have to save you" is a little harsh. He planned to take out the train, the wreckage was all his doing, whether Ra's wanted to go with it or not.