Guess what I and almost everyone else doesn’t do: that.
Machine guns aren't evil because they're regulated.
In 1944 hundreds of thousands of liberator pistols were air dropped to the French resistance to fight Axis occupation.
In Myanmar today, 3d printed FGC-9 rifles are being used by rebels to resist a coup staged by the military.
In Ukraine, as I'm sure you're already aware, weaponry donated by NATO and the United States is being used in combination with improvised munitions delivered by drone to resist a large scale genocidal invasion by Russia.
Weapons are tools, no more good or evil than the person wielding the tool. Freedom of information destabilizes monopolies on violence and empowers people to communicate, organize, and defend themselves from aggressors.
This is an objective fact.
> The person was trying to skirt the law and got caught.
What law? The law that says you can't distribute a chart of a lightning link? That's not a real law. The point here is that the ATF created the law out of whole cloth.
> Or let me put it another way: if this keycard isn't a big deal, why do gun owners care?
Are you serious? The guy is going to jail under the charge that he distributed a machine gun, for distributing legal information in a country that has freedom of speech as the first amendment. He didn't even violate ITAR. I have a shirt with the CNC instructions to create a lightning link printed on it. Should I go to prison too?
"First they came for the $some_group..."