Honestly, that piece boils down to, "I and my side take a vicious cycle view of human civilization, Human nature doesnt change and ultimately a bloody circle will complete itself. That current gun laws are an effective deterrent against total U.S. government tyranny. I am not going to qualify my thesis empirically(in fact side step it when I take on the counter-point) but you need to accept it and if you want to do anything about it, you need to ignore questioning our assumptions, and leave our guns alone. Instead, focus on the other liberal things I like and through that shared prosperity people will find guns antiquated...Even though I just argued earlier my side will never buy into that."
I appreciate the thoughtful attempt at thinking about this issue on his part, and I think he points out some things that may hold true for people on either side in terms of their reasoning, but by failing to incorporate empiricism into his argument, he left himself open to some easy deconstructions. On top of what seems to be a sort of self-defeating logic.
For instance he implies a hard line between shared prosperity and a reduction in the desire for gun ownership. Setting aside his own logical knot, in this supposed struggling economic times, where the gap between the very rich and every one else is at levels not seen in nearly a century, household gun ownership on a per-person basis has fallen. It certainly may describe some of the present logic of the gun owners that are around, that are buying more and more guns, but as a whole that doesn't seem to hold true in America.