Ah, UrRong. Although it is true that the majority of oil is composed of microorganisms and that the amount of oil produced by an organism is not an accurate measure of the total amount of oil available in the world, it is not so inaccurate to make assumptions about the total amount of oil available based on the amount of oil produced by a single organism as you contend.
In fact, as Nikhil so aptly demonstrated in his original essay, knowing how much fuel is produced by a single organism gives us an idea of just how finite this resource is. It is this aspect of Nikhil's essay that is so powerful and, though the conversion of "meters per goat" may be an exaggeration, it is this forceful demonstration that drives home the point that all life, no matter how small or insignificant it may seem, should be valued and conserved.
If a 70-pound goat can only produce a half-teaspoon of gasoline, no wonder we can't take our cars across the country without stopping for a fill-up! Moreover, this knowledge allows us to be mindful and make conscious choices when it comes to using products derived from these corpses. That's not so UrRong...as they say, every drop counts!