This article is so dumb I can only assume it is intended as a form of sarcasm, a spoof:
First - All the groups mentioned by the Brady Bunch are ALREADY prohibited from buying guns (and are generally found in the federal database used for the required background checks when someone buys a gun).
Second - Need I point out that the "Tree of Liberty" quote came from Thomas Jefferson - would we deny HIM the right to buy a gun?
Third - What good is the 1st Amendment right to free speech, if exercising it would lead to denial of one's 2nd Amendment right to self-defense?
Naaah...it's GOTTA be a sarcastic spoof. No Editor at Reason magazine could possibly be THIS stupid! Look for a follow-on article tomorrow, pointing this out.