Are we talking about the same national guard that mowed down unarmed students in the Kent State massacre? You'd be surprised what strong structure can cause a person to do.
Well, more the National Guard that's literally the same people as the armed rednecks in rural Texas. Keep in mind the National Guard are the "weekend warriors", only now many of them have months/years in actual combat zones and have returned to their home communities with those skills.
Not to mention this whole argument assumes the government isn't siding with the insurrection. Sounds like an odd point to make, but if there was a substantial redneck revolution, which side is Trump's government on? Who will be labeled the rebels?
It's incredibly risky to assume who is on which side of an actual civil war scale uprising. The chances of being wrong are very high, and the consequences are literally life and death.
https://en.m.wikipedia.org/wiki/Kent_State_shootings