The fact that a bunch of civilians with privately owned weapons would not stand a chance against a modern military is true regardless of one's stance on gun control. I don't believe that fact is a reason to disarm people but only that it's not a valid argument to make against gun control.
People who believe otherwise do so because they want to. They refuse to look at it objectively and accept the idea that their guns could defeat the government because they are seeking additional rationalizations for their position. Its adopting views to support a belief rather than to form it.
I believe we should have a right to AR's, AK's, etc but not because i think they are a defense against a tyrannical government backed by a modern military. When we use weak arguments that most find absurd to argue against gun control it hurts us more than helps as we are not taken seriously.
Sure, the full military might of the United States with the support and backing of the PEOPLE could easily wipe out a bunch of misfit hillbillies trying to overthrow the government. They could do that with one or two drone strikes with such precision it wouldn't even make the national news because it would just be sold to the media as a gas leak explosion. That's not what this (totally hypothetical) thought exercise is about though. That's also not what would happen in real life and what the 2nd amendment is for.