Recovering irrationalist: in your induction argument, my first stab would be to deny the last premise (transitivity of moral judgments). I'm not sure why moral judgments have to be transitive.

Next, I'd deny the second-to-last premise (for one thing, I don't know what it means to be horribly tortured for the shortest period possible -- part of the tortureness of torture is that it lasts a while).