They didn't. They never go that far.
That wasn't the issue facing the U.S. Supreme Court. The National Firearms Act of 1934 (which taxed Miller's shotgun) was being challenged as violating the second amendment. The question before the U.S. Supreme Court was if the weapon in question was used by the state Militia. They remanded it back to the District Court to make that determination.
"will reveal that Madison was referring to every man of militia age (over 17) capable of bearing arms."
Instead of reading Federalist Paper #46, the U.S. Supreme Court would have read The National Defense Act of 1916 which "transformed the militia from individual state forces into a Reserve Component of the U.S. Army - and made the term "National Guard" mandatory."
>>>Instead of reading Federalist Paper #46, the U.S. Supreme Court would have read The National Defense Act of 1916 which "transformed the militia from individual state forces into a Reserve Component of the U.S. Army - and made the term "National Guard" mandatory."<<<
But, since the National Guard was created under the power to raise armies, rather than the power to provide for organizing, arming, and disciplining the Militia, then the National Guard is not a militia, but a reserve component of the U. S. Army. In fact, National Guard officers are U.S. Army officers.
The true militia, according to original intent, and never altered by amendment, is comprised of every male capable of bearing arms. The fact that un-elected ideologes playing the role of 'justices' have usurped that power, or allowed it to be usurped, is another matter altogether. The same for the RKBA.