Any on-line venue is a place where mods and admins make the rules. You know them before going in. Their place, their rules. It’s the same when going into any bar. Some bars may allow rowdy behavior, others have strict measures.
In such places speech is a privilege and not a right.
The only remarkable thing here in this article is the size of the discord. The problem with huge size is that the amplification effect is a lot bigger and that tends to get noticed. In the real world you don’t have bars with tens of thousands of guests.
The last line you mention is true-ish if said rather derogatory, but if you value freedom of speech, you can also extrapolate that everyone has a right on their view of life, nothing little about it.
The problem that is not being mentioned is cause and effect. If your view on life is basically violent and emotional, that helps nothing when it comes to public discourse. In all my years when I was a mod on IRC, never did name calling or derogatory names further an argument or improve communication, except when we were maybe discussing the topic itself.