Earlier quoted context omitted.
The part under discussion appears to be a quoted earlier message; HOWEVER I would much prefer a link to a message plausibly at least to be from the same server as ESR's other messages. I would like a link to the source, rather than someone saying a given source happened to send X. I could not in a quick 5 min of searching through Eric S. Raymond posts on that thread, see the actual source that is quoted.
In the same previous thread, people say that the offending emails were deleted from the OSI archive[1]. This seems, to me, like a very bad move for exactly the reasons you're highlighting here. [1] https://news.ycombinator.com/item?id=22518473
For example, the source you link may have just attempted to reconstruct the message based on what can be seen in the reply. However the chain of authenticity has been extended to contain those who may have motive to unfaithfully reproduce or even fake a/the message. We can't know as the transparency of the archive is now also in question.
Edit:
Under the assumption the reproduction is faithful, my own personal OPINIONs...
Calling someone a loonytoon is uncouth, deserving a brief lecture for attacking someone rather than debating the ideals they happen to believe in at the current time (or in the past if it's a clear reference to such). (Edit 2:) Also in that paragraph, there's a term I'd hesitate to Google for not knowing it's meaning offhand... I'm not sure how good/bad it might actually be.
The vividly disgusting and offensive description (which could very easily have been added in the quoted reply) of rat* (censored) is something that a rational adult just shouldn't use on such a forum. If that's what OSI acted on, they really should be more transparent about it as well as their decision process.
Most of the version you linked on TechRights is otherwise speech that should be protected and encouraged. It is a protest and valid expression of feelings; save for some charged language.