I am thinking maybe the writers are trying to fool us by saying it was either Widmore or Linus and it could actually have something to do with the "field" that split the two planes. If you think about it. Hurley making statements that they are dead and such, the theme is very strong. Live vs. dead. You are renewed on the island right? So in a way if you leave your home (where you belong) you could lose hope and inspiration.
I am inclined to think Widmore is behind this, however.

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Amee Eliza