I don't really know what you're getting at here. Nobody is stopping anyone from saying things. If I want to say the sky is orange, I can write a post about it on my blog, send it out to my E-mail list, distribute it as a printed newsletter, write a book about it, or walk into town and tell people as I walk by them. Nobody is being muzzled.
What I don't have the right to do is force Platform X, Y, and Z to publish my speech on their platforms. Just like here. If I write something here that goes against HN's guidelines or if they just feel like moderating it away, they have the right to do it. They don't have to keep this post on their site. This is not tyranny.