"...are you allowed to say anything about it?" Of course. But away from the project. In the project, I'd say you're free to ask "has this been reviewed? why hasn't it been?" in an attempt to get things moving. If, in the project, the maintainer makes it about non-technical things, have the wherewithal to take it public and not continue polluting the the project's technical history.
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.
