Yes, they referenced the 1939 Miller case -- the part where the U.S. Supreme Court in Miller made reference to arms that had "some reasonable relationship to the preservation or efficiency of a well regulated militia."
And the Miller case referenced the 1840 Aymette v. State of Tennessee case where the Tennessee Supreme Court made reference to arms being "any part of the ordinary military equipment or that its use could contribute to the common defense."
Then (and this is the strange part) the 7th Circuit, making a bold assumption based on those cases, concluded that "arms" referred to militia/military weapons! Where in the hell did they come up with that?!
Well, next thing you know, they're saying that average militia/military member doesn't use a handgun for the common defense and, therefore, it's not protected as an "arm". The insanity!
"The one where a few Justices decided for all of us that the 2A protects only a collective right?"
First of all, the Miller Court never did say whether it was a collective right or an individual right. They were silent on that issue.
Second, this is what could happen when only a few Justices decide for all of us what the second amendment protects.
Third, if any court declared a collective right, it was the 1840 Tennessee Supreme Court.
Silent, because some things are absolutely clear. Sometimes the obvious need not be explained as such.
If anyone involved had any inkling that the 2nd Amendment was a "collective right", then there would be no question that Mr. Miller was NOT acting as a part of that collective. Mr. Miller was well-known to the prosecution and the courts as a habitual criminal offender, variously convicted of or suspected a party to bank robbery, murder, moonshine making, booze running, etc. - caught with the unregistered NFA item during alleged criminal activity, NOT anything anywhere remotely related to organized militia activity. Mr. Miller was plainly a thug with a gun, the furthest one could conceivably get from any arguably legitimate connection to a lawful collective to which a RKBA could conceivably be attributed. If any argument can be made for the "collective right" theory, it most assuredly and obviously did NOT apply to Mr. Miller.
Despite every level of government involved being keenly aware that Mr. Miller was utterly criminal in his occupation, and absolutely & plainly not a part of any legitimate "collective", how much time was spent discussing whether, gun aside, the 2nd Amendment applied to him personally? none. zero. zippo. nada. nyet.
Despite the court, being faced with a known violent habitual criminal offender, having plenty of reason to find any and all ways legally conceivable to deny this man any right to weapons of any kind, and the weapon in question being federally deemed dangerous enough to warrant (inflation adjusted) a $3000 tax on a $10 gun, did they in any way address the notion that somehow, in any way possible, the 2nd Amendment might not apply to this individual? cue the crickets - nobody questioned that Mr. Miller, legally vile to the extreme, had some sort of right to keep and bear arms.
The Miller Court never did say whether it was a collective right or an individual right - because it was inconceivable that the right could be "collective". Of course it was individual! Should the notion have had crossed the court's mind, or the prosecution's mind, it would not only have been addressed, it would have been the first thing used to deny Mr. Miller standing (contrast Parker, where the "standing" issue arose only as a vague side query by a judge, and in mere minutes grew such as to eject 5/6ths of the plaintiffs).
You're right: the Miller Court never did say whether it was a collective right or an individual right - any more than a modern discussion of geography debates whether the Earth is flat or round.