You might have thought they were stupid reasons but protecting a public good is a very important and challenging task. Unlike the FCC, spaceX isn’t accountable to democratic forces and can do antisocial things with the shared resource and there will be little we can do about it.
“Protecting the public” is the propaganda. In practice, you have a regulatory system that gives every minority interest an effective veto on development, disregarding the global cost/benefit analysis. In our case it was church microphones and other tiny minorities that held up deployment of technology to take advantage of spectrum white spaces.