Some say he could've killed them at any time, and that candidates were never safe. They say he waited to kill so they'd do what he wanted. (or that they'd not trust him... to what end?) Well, if he was going to kill 'em all anyway, then he didn't need them to get on a plane and leave. He just wanted them together to kill them at once? Why? Because he couldn't chase them down on his own in Smokey form? Doubtful. I think it's more likely that Sawyer's fiddling with the bomb would've been the loophole needed to indirectly kill a candidate. (i.e., Jack)

People also complain that this episode title was misleading, and only had to do with Sideways-Locke's surgery. I disagree, and think Jack's insistence to "Just trust me" proved that he's the one. I think Sawyer disqualified himself with the bomb, etc, and Sayid's comment to Jack further supports that. Desmond will probably be the one to flip whatever EMP switch is necessary to kill Smokey, but Jack is looking like Jacob's replacement.