Why did the star map lead there, instead of to the Engineer home world?
If you go with the theory that the Engineers were using Earth as a cultivation of some kind, and that they would "reset", or infect the planet when we got technologically advanced enough to reach out to them, why would you give them your home address? They left the directions to a military facility, which would be plenty equipped to handle any expedition party that would reach out, without endangering the home world. It's like leaving them the address to Guantanamo Bay instead of San Francisco.
This doesn't actually make any sense at all to me. If that's the line of thought, why would they leave behind any clues to space to begin with? They don't have to and it wouldn't make any difference. It's really just bad writing to create a plot twist unless there's a better explanation imo.
Why didn't he Immediately go nuts? Why do you think he didn't... The sense of urgency just wasn't there. He even gently touched davids head.
Lindelof is going to reveal on the commentary track on blu-ray that David actually set everyone up by insulting the guy's mother.
