"They/them" is fine in real life because I don't have to interact with 'them.' When I have to read it in text, that's when I'm going to get annoyed. "They/them" translates like literal dogshit in English for single subjects. It's the same reason I fucking hate Deltarune making Kris 'ambiguous.' It's just obnoxious and stupid. EVERY OTHER CHARACTER in this series has a defined gender, and Opera's clearly a hot guy. There's literally no excuse for this bullshit except "ooh, look at our token nb!!!"