People are free to express their dislike of the Greens or Purples on Twitter. And they'll catch the fallout on Twitter. Why should these conversations pollute the project documentation?
If the lead maintainer shows its true colors and refuses to become a decent human being, people will leave the project. If the project is truly important, someone will fork it and create a new project with a new community.
Personally (and selfishly), it comes down to this: years later, when I'm looking for a solution to a problem and $SEARCH_ENGINE returns an email thread, I don't want to sift through dozens of messages about the drama between the Greens and the Purples to find exactly the single line of script that solves my problem.
"Also, why is "fair game" a concept that applies..." I don't understand. Either you've misread me, or you're bringing in topics that I didn't address so I don't know what this is about.
What do you think gives you the right to demand inclusion?
It would require them to specifically search for information about the author, which I can’t imagine anyone doing. That, unlike posting something on twitter, would indeed be indecent.
I’ve seen many instances of project contributors being flamed because of their “bad” behavior on twitter or elsewhere, but have not seen anyone accused not judging a specific contribution based on its merit.
Also, why is "fair game" a concept that applies to whether misbehavior can be challenged and not to the misbehavior itself? If the contributor tweets, "Ew, all these incompetent purples keep making trash PRs," why should that itself not be considered outside the bounds of "fair game"?