Here's what I got from the episode. The Island only moved to those who were outside of "the radius" as Daniel phrased it. If you're on Daniel's boat when the event happened, the Island never moved from their vantage point. It was only to those outside the radius that the island would have appeared to disappear. Also, the Island itself is not jumping through time, everyone else is, execpt of the hostiles/others who are tethered to the island. This is why when Locke asks where everyone went, Richard replies, "we didn't leave, you did".