Who's sitting in the chair?

In reviewing the scene with Hurley looking into the house , using slo-
mo and freeze frame, it sure looked like Jack's father, Christian,
sitting in the chair!

If he's "Jacob", that could explain why he's alive again in Jack's
flash forward.  Jack twice refers to calling his father (once in the
pharmacy and when arguing with the new chief surgeon) in his flash
forward episode from last season.

If Christian Shephard is really controlling the island's forces, that
could explain why he's no longer dead upon the return fro the island.