And this isn't just a random expropriation. While I may have to cry myself to sleep at the thought of our once great nation having devolved into a bitchy slap fest by a couple of narcissistic man babies, the fact is that SpaceX probably wouldn't exist today without the US government, so with Musk having a temper tantrum and saying "I'm taking my toys and going home", the US government would have at least somewhat valid national security reasons to take over SpaceX.
Couple that with the fact that Musk is hated, extremely, by many folks out both sides of the political aisle, means that the rule of law concerns about a SpaceX expropriation would largely be ignored.