...whoever moves the island can't go back.

The reason I think that is because when Ben arrives at the Tunisian hotel, he is :

a) a preffered guest, indicating he must have stayed there previously. why else would he go specificaly there, and often enough to be the preffered guest?
b) tells the concierge he has been to Tunisia prior, but it's been a while, or words to that effect

True, he's bawlig his eyes out turning the wheel, but perhaps that is his sorrow over Alex. If there is one thing I've learned about Ben - much as fun as that makes him as a character - is that he almost always lies, misdirects and hides. And when cought in the one lie, he fabricates the next one.

Even with a gun to his head, he wont tell Locke he knows more about the monster.