Dave

As we all know no, the Man in Black was Dave in this episode. And I understand that he was trying to drive Hurley insane to get him to jump off of a cliff, thus scratching one more name from the cave wall. What I don't get is that MiB should know that if Hurley was to jump off of the cliff he wouldn't have died, because they can't kill themselves. He would have had to have someone push him over the cliff. So, my question is, What was the point?... other than being a great and incredibly entertaining episode that is.