I'm wondering why Locke would have to move the island to leave it? Plenty of people have left the island by various means. Richard presumably lives on the island, but has visited Locke as a child, etc. And I'm assuming he isn't ageless. I assume that Richard moves through time and space, and seemingly has more control over doing so than Desmond had. Maybe Locke learned the trick...
And, for fun,
Jeremy Bentham.