Sorry for the delay. HN is not a great forum for long discussions (on purpose, I guess). I've been noodling on this for awhile, and so maybe just blathering into the ether.
I'm not sure that subjective and irrelevant necessarily go together.
I guess the argument I'm thinking of is more this: my pronoun preference is biological, so if my chromosomes disagree with my pronoun preference why should my chromosomes govern communication protocols instead of the rest of my biology?
If these things are truly irrelevant, then the notion of gender identity is itself irrelevant and so, too, are pronouns, aren't they? (I mean, maybe not, but I don't see how one could say chromosomes don't matter but preferences do.)
One of the real challenges gender identity raises is that it acknowledges that the body actually means something. It also implies that language means something. Mind and body go together, and when they disagree some kind of resolution is needed. Language shapes reality, so when language contradicts that resolution the reality of my existence, my very identity, is threatened or negated.
If we stipulate that, I think we have to admit pronoun use really isn't neutral. It's not merely a matter of common decency and respect (although it certainly is part of that), but about what we think it means to be human and how we attempt to shape and react to reality.
My own thoughts here aren't super well formed, hence my line of questioning and (perhaps poorly worded and thought out) reasoning...but I do think it bears some critical examination.