I think he still should have tried to get out. Like the Heroes quote says: the future isn't written in stone.

Hee, well, no, I don't watch Heroes, but I totally agree! Just because Desmond said they wouldn't get off the island if he didn't die didn't mean there wouldn't be any alternatives! I think they could have figured out something. But yeah, it could be that he figured it would happen eventually anyway. Sigh.