I was very surprised to read the article, because peacock stirrups are ubiquitous in the leadline, short stirrup and small pony classes in hunterland, and were also common in Pony Club back in the day.
I even remember it being a requirement for kids to have them to ride in the pony races that ran at point to point meets, back when kids rode their own hunting ponies in those races, rather than the format that exists now.
I have never personally experienced, or heard of, anyone getting injured by them; but that doesn’t mean it hasn’t happened. And Armand Leone’s point is well taken, it’s such a simple change to make to prevent potential injuries, why not make the change?
I do think that for small children, the most practical thing to do is to change the design of the peacock stirrup to face the hook inward and downward.