(In my example, I specify that B refuses to use A's requested pronoun.)
My question then becomes what happens then civility has already broken down? Say, I think "cunt" is a terrible word to call someone, and my cohort in a discussion is from a region where it's a fairly normal word, like "jerk". As we discuss, my cohort uses that word as normal, and I take severe offense, causing the discussion to break down as my cohort also doesn't wish to "cater to" me. Now what, are we just doomed to never be able to discuss even random other stuff like chocolate vs vanilla ice cream?
I'd say that a reasonable person could say, "Where I come from, that's a really offensive term. Could you not keep saying that?"
If they just keep saying it, it's clear that they don't care. That tells you that they aren't a person interested in meeting you halfway. I don't need to discuss chocolate vs vanilla (or anything else) with someone who's willing to deliberately offend me.
But if they forget once or twice, and say it, not because they don't care that it offends you but just because it's become habit, and habits don't change instantly, then cut them some slack. Your words that you say by habit that offend others aren't easy to stop saying, either.
But if you're so busy "taking severe offense" that you can't respond like a reasonable person, then maybe you're the problem. You almost certainly are if you're enjoying taking severe offense. (I know, nobody ever admits to it. But I suspect that some people do, and if they were honest with themselves, they'd know it.)
[Edit: Missed your first paragraph. Refuses is different from forgets to. Again, though, it may not be that simple. If B forgets once, a hypersensitive A might label that "refuses". Or, B could really refuse, but claim "I keep forgetting" when called on it. Those two scenarios look fairly similar - you probably have to read tone of voice, facial expression, and body language to know.]
I see, so, pushing to the extremes here and I wholly acnkowledge I'm doing so- what do you do when A is in a position with B where B informs A that B does not care if A is offended, but also if A stops engaging, B proclaims that A isn't listening to them and therefore it's A's fault?
"With those who will not listen, it is useless to have a conversation." A should say something like "I deny your interpretation of the events of this conversation" and walk away. There's no point whatsoever in continuing the conversation. B isn't going to listen; B isn't going to argue in good faith; B is just there to score points.
Will B regard that as a "victory"? Sure, but there's nothing A can do to change that. Will B claim that A isn't listening? Sure, but there's nothing A can do to change that. The only thing A can change is how much aggravation and abuse A has to put up with. So A should just walk away.
My question then becomes what happens then civility has already broken down? Say, I think "cunt" is a terrible word to call someone, and my cohort in a discussion is from a region where it's a fairly normal word, like "jerk". As we discuss, my cohort uses that word as normal, and I take severe offense, causing the discussion to break down as my cohort also doesn't wish to "cater to" me. Now what, are we just doomed to never be able to discuss even random other stuff like chocolate vs vanilla ice cream?