Ya know, after reading that article, I think the FF might just tell us we are to dang stupid to be allowed the use of their constitution. If it is not self-evident that the right to keep and bear arms includes the right to buy them in the first place, which requires a seller, then we are indeed too stupid to be allowed the use of the constitution.
The constitution was written to be understood and applied by the common folk. There was no need to apply some Gnostic type analysis to imply the proper interpretation of the document requires special knowledge not available to the common man. If special knowledge were required, nobody would have had any idea on what the constitution said and the FF were not the sort to "vote it in to see what is in it."