You restricted it to "government intervention, not...private agreements." The freedom of speech extends to the private sphere.
> You're conflating freedom of speech with a duty to listen
These are inextricably linked in the classical form. In the Athenian tradition, there was a duty to listen [1]. (Though even then practicality made it far from absolute.) That traces through to the Protestation of 1621 [2] and the Founders' debates around the First Amendment (namely, between Madison and Hamilton).
Practically, of course, no duty is absolute. But a society where everyone screams into a void isn't adhering to the principles of free speech and expression. (I'll note that alongside the duty to listen is an implied duty on the part of the speaker to speak truly [3]. Spam is the epitome of the cessation of the latter revoking the former.)
I think you're confusing something along the lines of "parliamentary privilege" for freedom of speech. Various forms of government have imposed as part of their decision making process a duty to listen to various forms of official speech. That's not a component of freedom of speech though, rather it's a component of that specific form of governments process.
I'm not sure where you find a duty to listen in Athens, my best guess is you are pointing to the duty to attend the assembly, which fits this form of "parliamentary privilege" rather than a broader duty to listen. To contrast, by my understanding political commentary in the form of plays and the like were quite common in Athenian culture, and I'm fairly sure there was absolutely no duty to pay attention to those. I'd also note that even with the assembly "the crowd might raise a clamor and refuse to listen to a speaker advocate an unpopular proposal" (your source) which suggests little duty to actively listen even there.
The protestation of 1621 is directly related to parliamentary privilege (and why I labelled this the way I did, though I don't think the label fits perfectly, since it applies to many smaller government meetings than parliament).
I can't say I'm familiar with the first amendment debate you are discussing.
> You restricted it to "government intervention, not...private agreements."
I don't think this is the cause of our disagreement, but I'll grant you that that phrase was slightly inartful. E.g. there are authorities other than governments, like a local gang, who could impinge on freedom of speech with threats of retaliation, and to the extent that private agreements are enforced by an authority it's possible for them to do so.
> you're confusing something along the lines of "parliamentary privilege" for freedom of speech
Technically, parliamentary privilege derives from the Athenian model of freedom of expression. In the case of the latter, the privilege (and duty) extended to the whole demos. Politics were never “off.” (Well, unless you were a child. Or a woman. Or a slave. Or a foreigner.)
One can trace it from there to the Roman Republic, and most pointedly, from folks in the early Empire lamenting how private society proactively narrowed the Overton window to align with perceptions of Imperial preference. (The Senate floor was muzzled by dissuading private criticism, officially and informally.)
Those “classics” then went to England and France, and then to America and Europe’s colonies, and then to the UN and EU. TL; DR Freedom of expression in Western thought as I understand it.
> which suggests little duty to actively listen even there
It was generally notable enough to be recorded, which suggests a general restraint. Not an absolute duty. But more than a little.
> don't think this is the cause of our disagreement
I don’t actually think we disagree :). We just know more about different aspects of the same thing.
You restricted it to "government intervention, not...private agreements." The freedom of speech extends to the private sphere.
> You're conflating freedom of speech with a duty to listen
These are inextricably linked in the classical form. In the Athenian tradition, there was a duty to listen [1]. (Though even then practicality made it far from absolute.) That traces through to the Protestation of 1621 [2] and the Founders' debates around the First Amendment (namely, between Madison and Hamilton).
Practically, of course, no duty is absolute. But a society where everyone screams into a void isn't adhering to the principles of free speech and expression. (I'll note that alongside the duty to listen is an implied duty on the part of the speaker to speak truly [3]. Spam is the epitome of the cessation of the latter revoking the former.)
[1] https://www.stoa.org/demos/article_democracy_overview@page=a...
[2] https://en.wikipedia.org/wiki/Protestation_of_1621
[3] https://en.wikipedia.org/wiki/Parrhesia