Obviously, Militia membership was irrelevant to the court.
You seem to forget the charges in this case. Miller was NOT charged with carrying an illegal weapon. He was NOT charged with carrying a weapon that only Militia members are allowed to carry. He was charged with interstate transportation of a weapon without the required tax stamp.
The only question before the Miller court was whether the tax stamp requirement was constitutional under the second amendment. The lower court believed the second amendment protected ALL weapons and ruled the tax stamp requirement unconstitutional. The Miller court implied that only Militia type weapons were protected by the second amendment.
"you fail to realize that the Court was responsible for guiding the trial court with respect to ALL relevant issues."
Be that as it may, they didn't. As the First Circuit Court said in US v. Cases (regarding the Miller decision), "The rule which it laid down was adequate to dispose of the case before it and that we think was as far as the Supreme Court intended to go."
Fine. Then without a showing that the weapon was not useful to a militia, the jury would be obligated to ACQUIT without regard to any militia membership.
You persist in your mistaken notion that a law which is unConstitutional under SOME circumstances is therefor unConstitutional under ALL circumstances. That is totally false. Perhaps you could justify this stance.
If the Miller Court had decided that only persons who are militia members are protected by the Second Amendment, then the law could be applied to Miller and Layton.
You will please note that the Miller case addressed ONLY the possession of a short-barreled shotgun. EVEN UNDER MILLER, if the shotgun had been found to be protected, the law would still be enforceable with regard to other weapons.
You are forced to persist in this error because otherwise you would have to admit that the Miller decision is an individual rights decision.