I think Jacob never inhabited the cabin at any time, that MIB/anti jacob was lured and trapped there and possed as Jacob to manipulate the islands inhabitants and those in the outside world through richard, whitmore, ben etc to orchastrate the loophole to kill jacob, plausible or mad rant?
just on the jacob topic.....I don't think it was "jacob" that appeared to young saywer or young kate as the advice/influence/objects given was negative and deliberate, yet when jacob appeared to locke, jack and hurley it was different he was sorry for locke and gave hurley advice and a choice and looked to be observing jack, just seemed different "visit" at a different time also as kate and saywer were children.....just a thought!