It is cultural, not halachic.
Most new things that people claim are “Halachic” are really cultural anyway. It certainly wouldn’t shock me that sunglasses are unofficially “banned” (i.e. your children will not be allowed into school), even though there is no Halacha involved. Like DY said, it is a cultural thing, and culture often trumps Halacha.
Nisht – For the same reason that women driving, bicycles, metal eyeglasses, and other “non halachic” items have been banned. Another non Halachic ban is expected.
P.S. I am very interested in Dr. Hall’s opinions, even when I disagree (often). He argues from the facts, not by pointing to authority, which (unfortunately, and due to their own actions) loses credibility by the day.