When free speech is limited it is no longer free.
Free speech ought to be defended and fought for.
As it has already been exhaustively pointed out, this has nothing to do with free speech.
We have no right to post on KB, and the host has to right to determine which type of content may appear on KB. Like it or not, that's the reality, and if you don't like it, then move on.
There are hundreds and hundreds of examples of true free speech being dampened or denied in real life, and those are the instances where "free speech out to be defended and fought for."
The right to post a fantasy story about three uncles gang-raping their 12-year-old niece (an actual story posted here) is not a right that falls under the category of "free speech."
THIS.
Free Speech prevents the GOVERNMENT from limiting what you can say, as long as what you say doesn't immediately lead to a life threatening situation (such as incitement to riot, or yelling "fire" in a crowded theater). It does NOT protect you from a private company deciding what it does and does not want published on servers it owns, in the same way a brick and mortar business can ban you from the premesis for saying something in their store they don't like (badmouthing the store, loudly discussing topics they deem unacceptable, etc).
But government restriction IS actually at the heart of the problem here. The sites were taken down, not because the people who run the server suddenly decided they didn't approve of the content, but because they were threatened with LEGAL action.
It's the same as if a brick and mortar business forcibly removed someone from their building for doing something illegal, even if the authorities haven't been called yet. The business would do that to protect themselves from legal liability, even if the person's actions did not otherwise affect them.
Thus, the impetus comes directly from government pressure and not private sector choice.
No one -- not me, not you, not anyone else -- has the right to post stories or anything else on KB. You can't complain about being denied a right that you do not have.
I'm not saying we have a "right" to post anything here. What I am saying is that it's inaccurate to frame this as though it was the server's free choice not to host the controversial content and that government restrictions play no part in it.
The people running the server are under real threat of government punishment or criminal prosecution if they continue to host the material in question. I do believe that platforms have a responsibility to moderate the content shared on them, but at the same time, if no platform will host certain content because of government restrictions, then that content is effectively censored by the government for all intents and purposes.
Some technologies, like the telephone infrastructure, have become so commonplace and essential to modern life that they are considered "common carriers," meaning they cannot censor the content shared over them, but at the same time, they cannot be held responsible for that content. KB is by no means a common carrier, so you are correct that posting here is a privilege and not a right.
But since there are virtually no other platforms that will host the content in question due to fear of government restrictions, this becomes a discussion about free speech.