It was a conversation in a private setting with several participants, some of whom were trans. It started as a broad conversation about which pronouns should be properly used when. When we got to "they", one of the participants brought up a common pattern whereby people will use "he" or "she" consistently to refer to cis people whose gender they know, but "they" when they need to refer to trans people (with known more specific pronouns) in the context where they can't get away with misgendering. We all agreed that this is rude, but then I asked whether it would be problematic if the person used "they" consistently, without discriminating. That's when it blew up.