This is the big show! This should be where the court decides
what the milita is. They could duck that but I hope they find
the milita is adult citizens.
Almost. This is the pre-show where the court decides if there is going to be a big show.
Who the militia is is irrelevant, the amendment states that the "right of the people" is not to be infringed, not the right of the militia. The preamble states that the right is protected because a well regulated militia is necessary, but the grammar of the sentence does not restrict the right to the militia.
If their was another amendment which read "A well read electorate being necessary to maintenance of a free state, the right of the people to keep and read books shall not be infringed" it would not be OK to ban those too young to vote or not registered to vote, who are not part of the electorate, from keeping and reading books.