Too similar to the Iron Cross, was the reasoning I believe. Like the swastika—which for thousands of years had been a positive, often spiritual symbol—the Nazis ruined the symbol for western use.
I know a few people from India that still display a version of the pinwheel in decorative tapestries (which in their culture has always meant prosperity) as they can’t stand the idea of its meaning being permenantly changed by “maniacal genocidal monsters.” I can’t bring myself to associate with the symbol (with its true meaning, that is), but I understand the basis for why they do it.
Not sure we’ll ever have a kit harkening back to the St. Mark’s days because of that association, unfortunately.