Didn't Fire and Stone also show trees being grown by the Black Goo? Since there wasn't a forest when Prometheus arrived and now there's a biomechanical jungle.
Also I recall the human survivors mentioning how the food was getting more corrupted, I can't recall if the food was crops and plants as well as the animals. If it was plants, that could contradict with what David said about the Black Goo only affecting non-plant life. Unless his Goo was a modified version.