You say you're worried about freedom of speech in big tech companies and de facto digital public squares, but what you seem to be getting at would actually curtail their freedom of speech. The government forcing private entities to disseminate speech they don't want to — that's where this leads, right?
In reality, no one is a free speech absolutist. We just argue over where the lines should be drawn. Bans on child pornography and threats of violence are pretty uncontroversial abridgements of free speech. Banning harassment and hate speech seems to be a bit less popular. Which is fine, everyone has their own ideas about what's acceptable. But don't draw your line in the sand and then tell me that's what determines "free speech".
In reality, no one is a free speech absolutist. We just argue over where the lines should be drawn. Bans on child pornography and threats of violence are pretty uncontroversial abridgements of free speech. Banning harassment and hate speech seems to be a bit less popular. Which is fine, everyone has their own ideas about what's acceptable. But don't draw your line in the sand and then tell me that's what determines "free speech".