I don't see any confusion. I think it's a red herring. If someone asks me "When is Ren coming over?" and I say "They'll be here in an hour," there's no ambiguity in what I am saying there.

In French the word "vous" can be used in both singular and more formal plural second person, why can't English have they as both singular and plural? The only objections to that use showed up when people wanted to take difference to the decisions of trans people. It was used quite extensively as long as I've been alive as a singular pronoun when the gender is unknown or wishes to remain obscured, why is it such a problem when used to identify a non-binary person?