Robust, yes, and more than a bit arrogant too, IMHO.
Sorry, but that's your problem. BA doesn't give two hoots about Y passengers. It can sell that seat anywhere, to anybody, without an issue.
They could sell it but they might end up going with an empty seat at that fare. Our tickets are sometimes booked one day before the departure date so the chances for the ticket being unsold are big. And my colleagues are just doing the same now...
So BA doesn't care and we also don't care anymore to fly the percy nasty stingy airline. BA doesn't care about any passenger: Economy, WTP, CW or First! Good for Air France though!