Most military equipment and technology is built by companies. There are contracts and laws that prevent those companies from abusing that power.

If starlink is critical US military infrastructure, then the US government needs to draft a contract with SpaceX to supply that infrastructure where it’s needed, and enforce it. If (when) Elon abuses that power, then he needs to be held accountable.

SpaceX has many contracts with the US government, and is prevented, by law, from doing certain kinds of business with foreign companies. There’s a limit to how far he can push things without jeopardizing that relationship.

US military is definitely aware of this obvious problem and they’re probably in a planning stage of building out their own low earth orbit constellation of satellites that they fully control for military use. If I had to guess they’ll contract with Blue Origin to build out this architecture. Elon is shown to be a security liability at this point with alleged drug use and conflict of interest with countries deemed adversarial to US.