Also just to add onto the military thing specifically, logistics are a bitch and I'm pretty sure even if the entire military was mobilized from the paper pushers to the specialists to the grunts they wouldn't have enough manpower to occupy LA alone. The logistics wouldve had to be set up months ago so even if they do there's a solid chance they run out of fuel or food and end up buming around some random town that they aren't sent to.

The real risk isn't martial law itself, it's elected representatives getting killed or something similar. Though honestly speaking that also could trigger a succession crises or otherwise result in de facto loss of federal authority within some states.