Not quite.
As I understand it, in Miller's original trial, the lower court threw out the case after Miller's lawyer argued that the part of NFA prohibiting a sawed-off shotgun without a license violated the 2A. The judge agreed and threw out the case.
Miller then disappeared and the government appealed the case to the Supreme Court.
When SCOTUS heard the case, Miller's lawyer wasn't there, so the Court heard only the prosecution's side of the case.
The Supreme Court held, in effect, that the Second Amendment protects militia-type arms, and that in the absence of any evidence in the record about whether a sawed-off shotgun was a militia-type arm, the Court said that it didn't hold the NFA to be violative of the Second Amendment and sent the case back to the federal district court to determine whether a sawed-off shotgun had militia use.
In the meantime, Miller, who was a government informant snitch, had been murdered, and the only reason the case survived was because he had a co-defendant.
So all the Miller case really did was say that:
a) the 2A protects militia-type arms, and
b) without any evidence that a sawed-off shotgun has militia use, we're throwing it back to the lower court to answer that question.