It already is, just some people want want to extend the law to force people to think & behave the way they want them to. American law covers everything necessary for every individual to live a civilized life where they can pursue happiness and meaning as they choose to define it.
Can see that happening right here; some people have been downvoting and flagging this comment thread, even though it doesn’t break any rules as far as I can see.
Why stifle discussion like this? Don’t let HN become like Reddit where the downvote button is basically “I don’t like this.”
I think hate speech is a bit like drink driving. Perfectly harmless itself but can cause follow-on real world problems that do impact people's lives - ie discrimination in hiring/etc.