Right... so he could also, for example, decide that Starship will only take MAGA astronauts to the moon. And that's why taxpayer funds should not be used for developing Starship.
No he can't because the US is paying for that, it is the government's mission. And fwiw now the gray area of free starlink in Ukraine also taken care of, the US government is handling that contracting like they do with all weapons systems. Before starlink was made available for free in Ukraine for humanitarian purposes, but the military also obviously found good uses for it before the gray areas were resolved.
Starlink is his property, he doesn't need to be head of state to suspend a free service and that's how it should be.