During the June 13, 1954, episode of American television's What's My Line, the panel was blindfolded and had to identify the guests, Les Paul and Mary Ford, by asking a series of questions that the guests would answer. The panel didn't know from the outset that there was more than one guest. This conversation ensued (from timestamp 18:55 of this video):
Panel: Are you in television?
Ms. Ford: Kinda.
Panel: "Kind of." Does that mean that you're in television by way of movies?
Emcee: … it means they're in television — they appear on television screens, etc. — without any specific reference to time, date, etc.… It just means that you asked "Are they in television?"; the answer to that would be "Yes".…
Panel: Well, is this, um — hm, I think there's more than one person there.
Emcee: Well, if you do, all you have to do is ask the question.
Panel: Is there more than one person?
Ms. Ford: Yes.
Now, I would've thought the emcee had given it completely away: that, in 1954, referring to the guests as "they" would make it clear as day that there were multiple guests. Yet the panel asked. So am I wrong: was singular "they" at least somewhat acceptable (at least when trying deliberately to conceal the sex of a person)? Or am I right that "they" was only plural at that time, and the panel was merely being extra-cautious (or polite in pretending the emcee hadn't flubbed)?