Really just need to make it clear that while they were no longer at war with Britain, the war was not far in their past, and they all remembered it very well, including the reasons for it.
Even though they were now the government, for the most part, they still distrusted standing armies and government in general. As Ms. Malcom lays out, the reason for the second amendment, from a governmental perspective, is twofold, one to obviate the need for a standing army, which they considered extremely dangerous to liberty, and to provide a counterbalence to any armies that were raised under the Constitutional power (Art. I, sec. 8) to do so. (note the plural, armies, is in the Constitution. The Air Force can be considered an air army for Constitutional purposes) Evidence of their distrust can be found in the provision that appropriations for such armies can be no for no more than two years. Appropriations for a Navy (singular) are not Constitutionally so restricted. In the event Congress does appropriations for both for a single year.