That section refers to assembling parts from a parts kit, where the user has to supply their own receiver (which they have to 'manufacture').

And yes, I did read the very first sentence - you may not make a firearm _for_ sale or distribution - you can only make one _for_ yourself. That is the 'intent'. However, you can then later on (a rule of thumb I've heard is at least a year) sell it if you wanted - the original 'intent' to make it solely for yourself has not changed.

Note the second paragraph of that FTB letter I linked to:

Also, for your information, a nonlicensee may manufacture a semiautomatic rifle for his or her own personal use. As long as the firearm remains in the custody of the person who manufactured it, the firearm need not be marked with a serial number or name and location of the manufacturer. However, if the firearm is transferred to another party at some point in the future, the firearm must be marked in accordance with the provisions set forth in 27 CFR 478.92 (formerly 178.92).