A few corrections or comments:

McNamara and company forced the AR-15 on the Army (the Air Force was already buying them for guarding planes and the like, a much less demanding duty) because the small arms procurement part of the Army at the time was utterly corrupt, preferring inferior US designs like the M14 (too much operating stuff out in the open, otherwise a great improvement on the M1 Garand) and the M60 machine gun (details on request). They biased tests by e.g. replacing screws holding a rifle together with springs while they had custody of them before the official tests (or at least I've read that about the trials that selected the M14, the AR-10, original big brother of the AR-15, was said to be sabotaged that way).

The NRA never, ever, supported the "assault weapons" ban, with the sole exception of one off-script or trial balloon radio interview with Carleton Heston (take your pick, he and other Western actors cut commercials to support the passage of the Gun Control Act of 1968). This was much noticed in the community because Clinton's AW ban was the first piece of Federal anti-gun legislation that passed without the NRA's approval, however grudging.

"Accustomed to taking down trophy bucks with a hefty .30-caliber round, they ridiculed the AR-15 as a “mouse gun” and feared that its smaller .223-caliber bullet would only wound an animal, instead of taking it down with a single, clean shot."

A bit of an exaggeration, higher energy narrower than .30 caliber (7.62 mm) rounds have long been used to take deer sized animals. Prior to recent tremendous developments in bullet technology .223 was iffy except for smaller critters, it was in fact derived from the .222 Remington, a target and varmint shooting cartridge, at least in the US.

Any correlation with the expiration of the 2004 "assault weapons" ban and the civilian market's response is bogus. It was sufficiently weak that the only effect was an increase in the cost of magazines, and since it had been our issue rifle for a quarter century there were plenty used ones to be had. Otherwise you could buy one as long as you were willing to forgo e.g. a bayonet lug.... I think the big event was 9/11, and the feckless domestic response, e.g. Bush telling us to go out and buy stuff to support the economy. Many people realized they were on our own, at least in terms of initial response, and plenty of subsequent events like hurricanes emphasized that. E.g. there's the saying that "When seconds count, the police are minutes away". After a hurricane for many it will be more like weeks.

That Hello Kitty rifle is real, there are some very nice modern gun finishes that come in many different colors, like DuraCoat which was used for that one and which the article has a photograph of a SHOT Show advertising display for it.

I can't speak to the author's emphasis of all this coming from the gaming "and others who had fallen into the post-9/11, SpecOps-inspired 'tactical lifestyle'" ... but I'll note there wouldn't have been a 1994 "assault weapons" ban if these weren't already popular guns. I personally know they were popular in the '70s, and as Cam Edwards put it, "The AR was designed in 1957 and sold to the public beginning in 1964. Perhaps we should go ahead and ban that newfangled rock and roll too."

Obviously, the "NRA’s dire warnings of an Democratic gun grab should Obama win the presidency" were accurate, if the timing was a bit off. And Sen. Joe Manchin is a poser who doesn't know the difference between a magazine and a clip, unless his shooting experience up to now has been with single shot rifles and double barreled shotguns.