> how many people need to hear something before it qualifies?
Thats an easy question to answer.
The answer would be whoever voluntarily chooses to listen to that speech, of their own free will, without other people coming in to make significant disruptions (especially illegal disruptions, or acts of illegal physical violence) of that voluntary interaction between speaker and hearer.
> Are you arguing that downvoting a comment..... is HN infringing on a user's free speech?
A better example would be a 3rd party going to the server room where Hacker News is stored, destroying the servers with a hammer, and then saying "Your speech isn't infringed on! You were allowed to say whatever you wanted! You just don't have the right to be heard, because I the uninvolved 3rd party broke into the server room and destroyed the server hardware!"
Yes, if this is what happened, this is starting to get close to censorship. Especially if it is not a one time thing, and is instead continual or illegal.
Also, if you want a better explanation, just go look up how free speech works in the US.
All these crazy hypotheticals, that you think are somehow gotchas, have mostly been settled by the US court system.
And the US court system has side strongly in favor of protecting free speech, while also being able to deal with these very limited and rare exceptions, to prevent extremely damaging content, like direct and immediate calls or violence, or the like.
This has all been covered before, mostly, in a good way, by the US legal system and court precedent.