Replying to you, but also in general. The reason why Michael and Locke have “more work to do” is because they are in purgatory and they have not earned their way out yet.
To answer another poster the reason why it is wrong for Michael to kill others when others have been killed is because it is about judgment. The others have been allowed to pass along because the determination has been made based on their behavior whether they belong in heaven or hell.
Michael is well on his way to heading toward hell. He makes bad decisons for good reasons (saving his kid, protecting others) but in the end he is making bad decisions.
Just to be clear, I’m not a very religious person, but the theme throughout this show (to me) shows it is very well-based in classic Western Civ ideas about morality and the afterlife.
The creators of LOST have always denied the purgatory theory and insisted that LOST had the same amount of fantasy as a Crichton novel.