There's just a little bit of a difference between being polite and considerate and sensitive, and instituting speech codes and unbroachable topics and shaming anyone who transgresses.
This. Obviously you should try to be polite and not intentionally step on people's toes or offend people just to make some stupid point, but there are actual lines where some people go to crazy town because of it.
For instance, I've liked a lot of content from the site Mark Reads. I've spent hours reading a lot of the reviews there, and it's been insightful and entertaining, and all that jazz. If you ever try entering the comment sections, though, be wary that he bans such things as "ableist language." Meaning that if you ever use words like "crazy" or "idiot" or "insane" or "lame" or "mad" and others like them, even in the most casual, innocent way (ex. "I saw this movie last night and it was crazy awesome!") you can be straight-up banned for it. The same principle goes for a lot of the other -isms. That's what people get upset about as being ridiculously over-sensitive and being language and thought policing control freaks.
Well, he may be an idiot, but his house his rules etc. The thing about this sort of thing is that people try to pass it off as a freedom of speech case when, unless your "politically incorrect" speech involves death threats, the government doesn't give a rat's ass about your comments and will not try to censor you. You don't have the right to be heard and we have the right to not listen to you, and have the right to scold you or call you out if what you say violates the community standards society has set up over time.
Today, saying calling someone an idiot is a hateful remark is absurd. In ten years, society might have come to the consensus that that guy is right and calling someone an idiot is hate speech and might shun you and call you on the carpet for doing so. That isn't a curtailment of your free speech,
that's the rest of society exercising it's free speech and telling you that it doesn't consider your speech acceptable anymore. You won't go to jail, you won't pay a fine, but society is well within its rights to determine that a certain position or set of words are outside the bounds of civil discourse and shun those who use them. Your right to speak does not equal a right to force others to listen to content that they don't want to listen to, and they can and will tune you out or try to shame/humiliate you into silence.