Trish
VIP OAP
To be honest @Sunny, using "they" for an individual has always seemed odd to me but, you are right, we often do use the term "they" when referring to one person.I agree, Vaughan, but I think the confusion goes beyond the age of the listener or reader. Here's an example:
I was reading an advice column in the Washington Post, which knocks itself out using politically correct (woke) terminology. Someone wrote that his daughter, with whom he had issues involving the daughter's boyfriend, was coming for a visit, and he was asking for some advice.
The answer from the columnist was something like, "When they arrive greet them warmly, and express how happy you are to see them."
My reaction was: Huh? The daughter is bringing her boyfriend for the visit? But the person asking for advice didn't say that. How many people were coming on this visit? Just the daughter was "they?" What's going on?
Obviously, this was of zero importance to me personally. But imagine the confusion and misunderstanding that can be engendered if everybody starts talking like that all the time.
However, we interestingly do use "they/their/them" for a single person all the time when we don't know who they are. "Somebody must have left their wallet here."
In the case of someone addressing a colleague as "he" when they had asked to be addressed as "they", I do wonder why the colleague wasn't just introduced by name: "This is my colleague, Sunny".