Natural law has very little to do with this. We should consider this to be a highly instructive case, and a good warning for conservatives, who play into this sort of thing all the time.
The 9th Circuit ruling is entirely consistent with, and can reasonably be inferred from, the letter of the law, as written in the 2nd Amendment. Our side nearly always loses when we focus on the letter of the law, because this effectively surrenders the spirit of the law without a fight.
Mr. Blume's Natural Law argument appeals to the spirit of the 2nd Amendment. However, we've seen all too often that the left is not interested in accepting traditional statements of Natural Law, which inevitably bring into play the religious beliefs that the left does not accept, and is working hard to eradicate from society.
Blume's own hyperbolic "analysis" actually has less explicit justification than does the court's ruling. Unlike the court, which did at least engage the actual language of the Constitution, Blume continually refers to some amorphous set of principles called "Natural Law", but he doesn't offer any real description of why it's Law in the first place. (And his silly name-calling makes me want to wipe the spit off my screen.)
Blume's real problem is encapsulated by this statement: The whole basis of Western civilization is that the individual, free from the constraints of over-burgeoning government ....
This is not the basis of Western civilization. Christianity is the basis of Western civilization, and the whole theory of individual rights -- not to mention that of Natural Law -- springs from Biblical sources.
In the end, Blume's argument carries very little weight for those who do not already accept his version of Natural Law. That is the real issue here.