The main problem with the argument that a populace with small arms can't stand up to a large force is that history has shown it to be untrue. All you have to do is look to see that there have been times when a population with small arms has stood up to a larger, better equipped force and not been smashed flat. It's tactics rather than the arms that rule in that kind of engagement.
A second and more telling argument against it is that the US Military is made up primarily of citizens of the country. They swore an oath to uphold the constitution, not the administration or congress. Giving an order to fire on the population in general simply will not be followed, they also are of the people, not separate from them.