While the military version of Starlink upon which Ukraine relies was developed by Elon Musk, and Musk has attempted to exert influence on foreign governments for years, the system is operated by the US government, so it is unlikely that Musk is primarily responsible for the decision to limit Ukrainian access to it. Trump can take credit for that development if he has the nerve to do so.
But what will happen in the future if the interests of Musk and the US government are no longer aligned? Who controls in that situation: the man with the tech and the money, or the guy with the law and the guns on his side?
Musk will have more power than any single private individual in my lifetime to dictate policy after 2028, particularly if Grok becomes more capable than its competitors. More than anyone since J.P. Morgan, and possibly more than him. It is a scary thought for the future.