Posted: Sep 16, 2019 8:35 am
by Spinozasgalt
I can't really see it. In that article it only notes that Chaucer, Shakespeare, Austen etc. used the "singular they". It doesn't ascribe to them the definite or indefinite usage. And it provides this:
dictionary.com wrote:Fast forward to this century when The American Dialect Society’s 2015 Word of the Year was the gender-neutral singular use of they. This vote, as it happened, came just after the late Bill Walsh, a copyeditor at the Washington Post, announced that the newspaper’s official style guide now allows the use of gender-neutral singular they. He called the use of they “the only sensible solution to English’s lack of a gender-neutral third-person singular personal pronoun.”

That, especially the last part, seems to note that this is new usage building on old precedent. I would say, at worst, that they're just guilty of some ambiguity.