Ex nihilo means "out of nothing," and in particular I am using it to refer to an assumption of superior, asymmetrical rights (rights I have over you that you don't have in kind) that come from absolutely nowhere. If I claim ex nihilo rights, I'm just claiming they exist, but I can't explain why or how I got them in any philosophically consistent manner. The point here is exactly that there isn't some contract or consent from which they arise.

I think he must necessarily be assuming that an organization called government can, for some nonzero period of time, be completely objective. He talks a lot about "objective laws," but that's silly: fiat laws (laws created by humans) cannot be objective, by definition: an inherently limited and subjective creature created them. Objective laws do exist (those that govern physics, cause and effect, math and logic, etc) but humans don't create or influence them.