[mynameishere]

Grammar and style are both ultimately dictated by usage, so if someone insists on plugging in XYZ as a new ultra-PC pronoun I can't really prove that it is incorrect, no matter how ridiculous.

So, that said: The whole point of using "they" is when you don't know the gender of a person and don't want to presume by saying "he" or "she" or muddying up the text by saying "he or she". When you know the gender of a person, using the correct pronoun is better--it's both succinct and corresponds more closely with reality.

It's a touchy subject [I mean, some idiot flagged my comment--come on!] but people tend to over-correct in grammar quite a bit, and over-correcting with "they" happens like this.

[gil]

Got it, thanks.

Perhaps the parent was trying to conceal the identity of the person in question and gender would be too much of a giveaway.

[sctb]

It's less of a touchy subject than a predictable and boring digression. Users often flag off-topic comments.