Everybody ignored Laufey's great comment pages back, which makes this theory create just as many holes as it tries to fill.
It was a great, great read, mind you, but unless they had a human to interact with 2,000 years ago on 223, the theory about the goo doesn't hold any water, unless it "interacted" with the jockeys differently because they decided to kill humanity rather than create life.
It also all depends on whether the goo at the beginning is the same as the black goo in the temples.
An interesting bit can be found on the projectprometheus web site, under Project: Genesis. You can download Shaw's research dossiers, and one of them shows an Urn they found on earth, petrified, from circa 2,500 B.C. This means that not only was the goo already on Earth, it was supposedly found 2,500 years before the engineers decided to wipe us out.
Perhaps they were testing it? Was this the urn that the sacrificial jockey got his goo from? If so, it's pretty clear that it's the same goo. If that's the case, the psychological aspect that dude pointed out seems the most likely, making the goo an intelligent organism that reacts with its' hosts base nature.
But then that raises yet another question, in that if the goo reacts as such, and the Jockey had to prepare himself for the sacrifice that would create life, what was up with Holloway? He clearly chose in the end to sacrifice himself, for one reason or another, and this would be the equivelant to what the sacrificial jockey had done.
More missing pieces.