I'm not sure either. HN, or CSAIL mailing list, are community chatrooms that sometimes spill out into the world at large, but their day-to-day activity concerns their respective communities. You do not expect to see what you wrote there aired in mainstream news.
> I'm also not sure whether "private conversation" matters a lot.
I suppose it doesn't in the case of publicly recognizable people or public officials; this sort of comes with the territory. But what private (or semi-private) conversations introduce in this picture is a "kill chain" - a chain of people or organizations involved in taking a private message and turning it into a mob forcing one's employer's hand. I think it's worth to take a closer look at that chain - especially in this case, where you can clearly witness an increasing level of misrepresentation happening. The original post, for instance, stayed just a bit shy of making accusations that could be subject of a libel lawsuit, implying but not stating a lot of things. And then the media coverage did its usual misrepresentation amplification.
To be clear, I'm not arguing for shooting the messenger - just that there should be some pressure in the society which ensures messengers are communicating their messages accurately. Ironically, the subject of this outrage is that pressure - RMS attempting to correct inaccuracies.
> If I was so upset with someone that I felt the need to go to their employer and complain about them, that seems like my right to free speech and expression. If, after security kicked me out, I took the matter to the local newspaper and it caused an uproar, that also seems like my right.
Depends on the reason for you being upset, I would hope that the paper would either pick it up and air it, or laugh you out of the room too. But you're right, it's technically your right to try. But still, I think there's something wrong with trying to end someone's career - thus causing significant, real, material harm to them - just because you personally found their speech offensive. It's like a lightweight form of swatting someone because you got angry.