It's a complicated question, but there are echoes of it in "Why does the US get the privilege of having their flag on the moon, just because they could get it there and nobody can take it back down?" or "Why do people have any right to the land they occupy, merely because they got there before other people did?"

First-mover advantage is real.

It’s not complicated. The answers to your questions are, “Because they can.” Possession, control, and force carry much more weight than some would like. It just makes those without power, authority, or any other stakeholder equity uncomfortable.

The US is not a super power because it asked politely and a committee granted it permission. Similarly, SpaceX will move forward because anyone with the authority to challenge them allows them to proceed.

What is the SpaceX constellation enabling that others aren't? Hint: theirs is not for consumers.

You're not wrong! The US DoD is already paying StarLink for proof of concept work for low latency, high bandwidth connectivity services.