Both Murdock and Follett involved Jehovah's Witnesses and the question was whether they needed a license to be allowed to go door-to-door and distribute literature. Interestingly, one year apart the SCOTUS found for Murdock in the first case but for the town in the second. The difference seems to be that in the first case the books were offered for free and donations were requested. In Follett, Mr. Follett was selling the books as his sole means of income, and refused to buy a $1.00 to be allowed to sell door-to-door.
Doesn't look like either has much to do with the RKBA. I don't know why the individual on MD Shooters was so excited about these cases, and I apologize for having mentioned them before reading them.