Fatigue will be the only real casualty factor. The vast majority of homes will be defeated without even seeing the enemy. And we're only talking about infantry here.
One tank rolls up. Fires one round. From a mile away. At night.
One drone flies over. Drops one bomb. From a mile up. At night.
The only role the one hundred infantrymen have is to make sure no one gets out of the house.
If the state government actually gets the national guard on its side, and they are willing to kill their fellow citizens I don't see how they can lose unless the unorganized rabble gets organized and rudimentary trained in warfare... And take the fight to the state. I.e. march on the capital and destroy the government before the military can kill them all.
You're not wrong, however I'd submit a few things too.
You're forgetting that there is already 10s of thousands of trained vets in the population, many former SF people trained specifically to be force enlargers by rapidly training others. I'd bet there is 100,000 people in this state who have had some level of professional training, and it wouldn't take much to spin them up to something that would give a real headache to any military action. While you're 100 infantrymen are the deployed force on the ground doing whatever, a few diversions here and there and you can move up a very, very large armed force from a line of departure to attack position pretty easily IMO, which would quickly overwhelm and defeat those 100 government soldiers.
In terms of dealing with military drones/etc, there is probably stored munitions in lightly guarded facilities that lots of said civilian vets are aware of, and it wouldn't take much to seize those if the people decide to act first (I'm talking about manpads and other handy items like anti tank missiles, Javelins/etc, that aren't available to civilians). Whatever the case may be, I sure wouldn't write off a pissed off populace so quickly. Look what the insurgents in the mideast have been capable of, without a 1/10 the resources available to US citizens in terms of weapons, ammunition, supplies, and training, all 4 of which a significant portion of the armed citizens have stockpiled for years.