Unless I'm misunderstanding the quote, that's very much not answering my question: it discusses limiting reach (i.e. ability to disseminate one's views widely and easily) and explicitly not free speech itself?
Free speech doesn't have a single meaning. Freedom is relative. There is no right to absolute free speech anywhere. For example, you can't yell "fire" in a crowded theater. On social media owned by private corporations, "fire" isn't the only thing you aren't allowed to yell. Subverting democracy, inciting violence, propaganda from foreign governments pretending to be grassroots movement inside the US, etc., are all banned, and yet I would consider Twitter a free platform, albeit with sensible limits. But you're right, that's not absolute freedom.
Fire in a theatre came up in the context of squashing a protestor against the draft, from a judge who thought eugenics may have something going for it.
How can you separate speech and reach in this specific case? Twitter could allow all speech but limit reach, ie shadow ban. Would that satisfy your notion of free speech?
Communication, as the atomic element of networking, requires both transmission and receipt to be said to have happened.
Speech is transmission.
Reach is landing at a receiver.
Substituting /dev/null in place of a human being does not satisfy speech having occurred. A concordance must be reached between the speaker and at least one other individual.
