The case before the U.S. Supreme Court was whether or not the NFA was constitutional. Specifically, whether or not the tax stamp was an infringement under the second amendment.
The case had nothing to do with either a collective or individual right. Are you sure you even read it?
Insofar as you could still pay the tax on new product, you would be correct. But since they closed the NFA registry, it now violates BAILEY v. DREXEL FURNITURE CO., 259 U.S. 20 (1922).
The last thing the gov't wants when shielding laws on the books is for anyone to actually address the law directly. Far easier to disqualify the challenger than to defend bad law.
And yes, the case was about whether or not Mr. Miller was allowed to keep and bear a sawed-off shotgun - at least without taxation. Every indication in the Miller ruling is that if the weapon in question had been shown to have some connection to common militia use (say, it had been a machinegun instead - easy enough to show), then the NFA law would have been deemed infringement under the second amendment and, as a result, Mr. Miller [would be] allowed to keep and bear a sawed-off shotgun.