The logic behind the ruling is summed up neatly
by Ilya Somin:
I'm not arguing that corporations themselves are "persons" with constitutional rights. Rather, I'm asserting that their owners and employees are such persons and that that status enables them to use corporations to exercise their constitutional rights. Similarly, partnerships, universities, schools, and sole proprietorships aren't people either. But people can use them to exercise their constitutional rights, and the government can't forbid it on the sole ground that they are using assets assets assigned to "state-created entities."
Somin points out that media corporations - and just about everything else - is a "state-created entity." He also identifies this slippery slope:
If people using state-created entities don’t have free speech rights, they don’t have any other constitutional rights either...Thus, government would not be bound by the Fourth Amendment in searching corporate property (including employee offices). It could take corporate property for private use without paying compensation because the Fifth Amendment would no longer apply. It could forbid religious services on corporate property (including that owned by churches, most of which are after all nonprofit corporations). If the Free Speech Clause of the First Amendment doesn’t apply to corporate property, neither does the Free Exercise Clause. And so on.