This xkcd comic makes the mistake of conflating the right to free speech and the 1st ammendment. The 1st ammendment exists to protect the right of free speech from the government, but the right is god given.
If a big chunk of your society make a habit of censuring people for disliked speech, organizations that are in the business of relaying speech make a habit of dropping customers over disliked speech, etc? Then your society is not practicing the principle of freedom of speech.
The stupidest thing I've read today
I feel like the XKCD perfectly reflects the free speech arguments I see online.