Theory 3: Walt's still alive and well, possibly in NY City with a close trustable family friend. Michael is helping Ben because he is ridden with guilt over what he did to Libby and Ana Lulu and wants redemption with the Losties, so he is doing what he can to help them off the island too.
I know, for some reason my creative mind is running wild today with theories. . . . may not be true, but at least they are making me think ;-)
***ding-ding-ding!*** We have a winnah!
Good call! Awesome job to pick that out ahead of time!
