It is a de facto attack on the 1A rights of that network. If you had a business on an island, and the government said "do business how we like, or we will close the bridge", then they are not restricting access to a public road for public safety. They are attempting to control your business, and using one of their tools to do it. Certainly you can buy a ferry and do an end around. But they have forced your customers to change their habits, which some will not. And you then have to make a major investment.
Telling CBS, for instance, they can't use the frequencies they own because you don't like what they say is restriction on the press. And it is unrealistic to say it isn't because they could just print a newspaper instead.
Frankly the FCC has one narrow purpose, and it isn't to decide what goes out on the airwaves. They simply make sure certain types of organizations are using the frequencies within certain bands, and then that not more than one user is on a particular frequency. In other words, they simply exist to prevent conflict. Anything they do beyond that is a waste of tax dollars and an over reach of government.
One quibble. No commercial entity owns a portion of the radio spectrum, they are licensed by the government to use it. That priviledge can be revoked, which is why the government can still control some behavior (profanity, adult programming start time etc)