That kind of reductionism is not helpful. It's not so simple as "private companies are free to do as they please". In fact many restrictions and regulations can and must be made to ensure that those private entities don't: poison rivers, murder people, manipulate children, steal from costumers, and countless other things. In principle at least, because we know that there are innumerable examples of companies doing just that when it profits them.

Nonetheless, among such regulations, designed to make private companies somewhat work for the general public interest, we can include not aiding censorship.