FWIW, I tried to get in the habit of using singular-“they” for everyone, even where I know their gender and they are cis, to reduce any subconscious gender bias. This has had two effects: learning that some trans people really don’t like that, and everyone assuming my partner is a dude. (He is, but I’m bi and therefore this is mere coincidence).

Interesting.

I've taken to calling my partner "partner", to be gender neutral. But in the short term, people probably incorrectly infer I use the term because I am gay. Or, if they're presumptive but less presumptive, gay or bi.

Has he objected? If he is voicing his opinion on his blog, but the policy for GNU (which he runs) is otherwise progressive, then it feels like he is separating his personal opinions from how he operates a professional venue.