That's a good analysis but somehow you (seem to?) end up at the wrong conclusion that the community has a single norm about this. What I see is a deeply divided community. The hopeful aspect (maybe) is that it's (perhaps) inching its way into more substantive discussion across those divides. That's a capacity the community has to build extremely slowly. The flagging phenomena that people are observing in recent threads are both a sign of this and integral to it.
There are exceptions, but most of the comments being flagged contain some element that is destructive of thoughtful conversation. Having those be marked as beyond the community's tolerance—and I mean 'tolerance' literally, as in, 'more than this will cause the nervous system to go into overwhelm'—is critical to de-escalating the remainder of the discussion enough that people can disagree without ceasing to hear each other.
The important thing to realize is that most flagged comments are not being flagged purely because of the point of view they express. In most cases they add a little extra something—or maybe a lot of extra something—and there are other, unflagged comments that express similar points of view, just more thoughtfully. In most cases, if the flagged commenter got calm enough to explain their point of view more neutrally, the odds of getting flagged would be less. (Inveterate trolling is also a thing, of course, but rarer.) They're welcome to do that and rejoin the land of the living at any time.
It does tend to require some work of self-reflection, though, to avoid getting flagged straightaway again. Most elements that result in flags are things the commenter was unaware of, but which land rather abrasively with the reader. The work is to develop some awareness of what those things are and then avoid them. For bonus points one can consciously replace them with something indicating respect for the opposing point of view or person. That can often be something quite small.
It is true that the ideological distribution of the flagged comments is skewed, but that's a separate question. And there are flagged and moderated comments on every side of the issue.