A few months ago we were talking about Facebook and Twitter censoring bigots, and a lot of people responded that it's fine when a corporation does it on their own platform--they own the platform and can do what they want with it.
My position was that when corporate platforms are such an important part of our communications, protecting free speech on those platforms remains important even though they're corporately owned[1]. It's easy to be pro-censorship when you agree with the censors, but corporations are amoral and if we set the standard that censorship doesn't matter, there's no guarantee that they'll only censor the way we want them to.
Consider this an "I told you so" post.
EDIT: More on this subject, perhaps a bit better-thought-out: https://news.ycombinator.com/item?id=21194433
[1] I'd further argue that we shouldn't give up so much of our communication to corporately-owned platforms for this reason, but that's a separate discussion.