[D-Roc]

I think his suggestion here came from his knowledge of the 2nd protocol - but how he knew about that is indeed open to speculation:

It could be related to The Constant - where Desmond came back in time and gave past Faraday "new memory" of future events. Specifically they seemed to place extra weight when Des told Faraday that he ends up on an island..

Also, we have Faraday's flashback in CD where he's crying. I'm wondering whether moving the island could have also moved Faraday back in time and space slightly, and this is why he 'doesn't know' why he's crying..?