This is an interesting take. But this paragraph presents an argument that is not sound.
As of 2012 the number of sworn law officers both state and federal was about 1.1 million. that’s 3.43 Officers for every 1000 people.
If all citizens are armed with fully automatic rifles, then law enforcement would be horribly outnumbered. The firepower that police can bring to bear in that case, as hypothetical as it is, isn’t going to change that.
Going down to realistic examples
If gun ownership is around 30% which is the mean estimate I can easily find, then we are looking at ca. 117 million households that have at least one firearm. That is a larger number than the total amount of sworn law enforcement officers by roughly a factor of 100.
That’s a huge disparity that was obviously not part of your calculus. Did you know that Law enforcement in the America is that outnumbered?
Furthermore, we can zoom back out to the argument from either absurdity or horror and imagine tanks in the streets, and hellfire missles being used to silence HAM radio operators etc.
If we get there, it wouldn’t have just occurred in a vacuum. And it would be too late for discussions of balances of power or detente between an armed people and the state. So TIS is actually out of the bounds of the discussion in terms of preventing TIS if the point is to avoid TIS.
A government willing or empowered to attack civilians with their own military needs to be checked by the threat of force before they attack, not after.
Just by looking at the rough math though, I, and I hope that you too can see that this paragraph, which is very important to your argument, is not as strong a foundation as you have presented.