So I'm not sure that they're doing a great job on that "only censor some of the unpopular opinions" thing.
They are in the sense that censoring an opinion strongly enough is one way to make it unpopular.
While it may occasionally happen that people justify their anti-ethical-value-of-free-speech behavior with "but my opponents did it first!", if their opponents were very conscientious about the ethical value of free speech those people would probably just decide that the ethical value of free speech was an Enemy Thing and people who support it are evil.
You seem to be unclear about how iterated prisoners' dilemma works.
For example, if I were friends with someone and they decided to tell me my hair was ugly, my blog is stupid,
(..)
This is because it is actually wrong to insult your friends.
What does it mean for something to be actually wrong? And how would one go about finding out which things those are? Does it matter if your hair is in fact ugly, or your blog is in fact stupid? (BTW, it is in fact stupid.)
For example, a lot more people believe that it is actually wrong to have sex outside of marriage then would agree with whatever your ideas about what's actually ... (read more)
They are in the sense that censoring an opinion strongly enough is one way to make it unpopular.
You seem to be unclear about how iterated prisoners' dilemma works.