It is, by definition, censorship. It's not _government_ censorship, but it's still censorship.
Companies need censorship to make money. They shouldn't have to lose money simply to satisfy your or my idea of not censoring.
Now the government? Yeah. That's a whole other issue.
Companies need to trample on your human rights to make money.
Now the government? Yeah. That's a whole other issue.
False. Freedom of speech outweighs property rights and the right of corporations' "Freedom of association."
Consider the situation in Australia, where all ISPs acted in concert to block websites. It's technically not government censorship, but the effect is the same - so any utilitarian rationale behind restrictions on government censorship should apply here equally.
Or maybe this should just be considered a form of illegal cartel.
"The censor was a magistrate in ancient Rome who was responsible for maintaining the census, supervising public morality, and overseeing certain aspects of the government's finances." https://en.wikipedia.org/wiki/Roman_censor
When its not government censorship it's called self-censorship or something entirely different.