historically the federal govt called up the state militias.
I just read washington warned on his deathbed that militia were not well trained... and two year later the U.S. formed West Point.
But, so what.
"A well regulated militia being necessary to the security of a free state, the right of the people to keep and bear arms shall not be infringed."
....the right of the people to keep and bear arms shall not be infringed. This was not a new idea it was based on English common law. The right to self defense and resistance to govt oppression and tyranny was seen as a natural right. Its why america was founded.
Nothing new... of course a person looking at original intent would not find the first clause restrictive.
You have the Courts Majority Opinion exactly right now. As I read it anyway.