Just watched the season finale repeat last night. Made me wonder about two questions:

1) Why did Jack decide Locke was correct and they needed to make up a false story? He said it was to protect the people who were left behind. But if the island was moved, how were they threatened? And why did none of the other members of Oceanic 6 (e.g. Sayid) argue the point?

Was it because they were afraid that whomever sank the fake plane in the ocean would come after them?
Because no one would believe them if they tried to tell the truth?
Or because Jack wasn't convinced the island had been moved and thought Widmore would send another group of mercenaries to the island?

2) Once Keamy was dead and Ben figured the freighter would blow up, why did he still go ahead and move the island, costing himself his place on it?

Because Jacob told him so and Ben is afraid to openly defy Jacob?
Because Ben was afraid of Widmore sending another team, now he knows the island's location and would rather take his chances in trying to get back to the island than see Widmore take it over?