Disclaimer: I'm strongly in favor of gender neutral language. I do personally use Singular They because it's the least obtrusive and most correct, but consider ey/eir/em to be a decent alternative (they feel like the most natural schelling point to me if you were going to pick a new word, and tend to be read as typos or completely glossed over during the interim period where they'll still gaining traction, whereas xir/zer/whatever just look weird)

I am persuaded. "Ey/eir/em" are Cool not-quite-words.

At this point the political-tangeant-sposion's already happened and I figure I might as well explain myself

Analytical tangents are also cool. Your parent was not especially political - at in particular it was only directly in favor of the new words rather than abusing those words to push a different agenda. When divorced of any other connotations a simple word preference is not especially dramatic.

Pro-gender-neutral-folks shouldn't have downvoted you for having changed your policy.

My best guess was that it was people trying to punish me for acknowledging that I formerly had that policy (and the usual two or three downvotes that I expect most of my comments to get from people I have pissed off recently - perhaps a couple from Clippy). But, as I noted, my model of human behavior in the context was completely broken so I had little confidence in that prediction.

Pro-status-quo folks who are upset at you for "having mellowed" would a) strike me as INCREDIBLY ridiculous, b) really should have explained their motivations if they wanted to punish your defection in a meaningful way.

I would have loved hearing that if that was the case.