Problem is he ignores that the beginning might not be earth, Janek's theory, and the fact that while the jockey might be 2K old, that doesn't really say anything about the facility itself, and the fact that the opening liquid and the liquid at the time of David's viewing of it are virtually identical.
If it was earth, it would mean teh aliems and jockeys are really really old, which makes whether earth is to be destroyed/rewritten or not a lot less significant. (Except for people living there of course)
He also missed that Ian didn't whack anybody until Shaw got whacked herself.