Elon Musk would prefer to focus on Mars colonization and development.

The Golden Dome is a planned missile shield that will need thousands of satellites to constantly monitor for threats and then to have systems to counter any missile attack. SpaceX already launches over 90% of all payload and satellites to space. When the SpaceX Super Heavy Starship is working as a fully reusable system then SpaceX will be providing well over 99% of all space launch capability.