And SpaceX is literally the only means by which the US is able to send astronauts to the ISS currently.

Incorrect. The US can and does send astronauts on Soyuz. One of the astronauts currently on the ISS arrived on Soyuz. Additionally, the US chose this path irrespective of companies and vendors when they chose to stop flying the Space Shuttle. You can't blame SpaceX for being successful and Boeing for being unsuccessful as justification to seize a private company.

StarLink is a strategically critical service for military and probably other purposes.

That is true state for hundreds of services providing by private companies to the US government. Why aren't you arguing to seize or nationalize those?

I was arguing a point, not a position.

So this whole thing is an exercise in pedantry?