Private companies aren’t restrained by the first amendment anyway, only the government is.
That is explicit in the text. However, IMHO you have to allow for the possibility of privatized tyranny - we dont want the government systematically allowing thugs to do what the government itself is not allowed to do.<sarcasm>Not that that would ever happen in America . . .</sarcasm>
That could only happen in Nazi Germany, Fascist Italy, or some other Obamanation.
When companies become too much of a monopoly, I argue that they should be restrained by the First Amendment.
Thought-experiment: Let us imagine, that in the 1970's, that AT&T banned all conservative talk on our phone lines, and managed to find a way to enforce that?
Or, that in the 1870's, that Vanderbilt banned all Republicans from his rail lines?
Google and Facebook are clearly in that league of monopoly.