i am not totally sure. I believe that the first amendment gives us the right to a citizen militia, freedom of assembly.
they actually talk about on pages 22 - 28 or so
http://www.scotusblo.../06/07-2901.pdfessentially the concern was that we would have government sactioned militia's only.
so the concern with the second amendment was at the individual level. also they saw the right as a fundamental "ancient" right, and necessary for the formation of a militia. essentially, ideally every amreican adult would own a gun and the entire population would be a militia to defend ourselves against a tyranny of our own making.
actually i really encourage you to read there decision. It is really good.
well thats why i said it would raise qwuestions as to what constitutes a militia, IE can a single person declare themselves a militia, or does it have to be a corporation like blackwater international (which of course then brings the issue needing government approval to form a militia, which as you say, defeats the purpose of the second amendment)