http://en.wikipedia.org/wiki/Amateur_Sports_Act_of_1978The Act charters the US Olympic Committee, which in turn can charter a national governing body (NGB) for each sport, such as USA Swimming, the United States Fencing Association, the United States Ski Team, USA Track & Field or the United States Figure Skating Association. Each NGB in turn establishes the rules for selecting the United States Olympic Team and promotes amateur competition in that sport.http://about.ussailing.org/History.htmAccording to the original constitution, NAYRU's authority stemmed from consent of its members and member associations over which it exercised jurisdiction in an advisory capacity. Today, its authority comes instead from an act of Congress (the Ted Stevens Olympic and Amateur Sports Act of 1978) and a much broader charter to serve America's sailors directly.
The Stevens Act has to do with the Olympics. If your aren't an Olympic athlete are trying to become one it has no explicit control of your sport. There simply are no "sailng police".
It seems to me USS said, "Okay, we have broad powers regarding the Olympics, let's just take over everything until someone challenges us." The USS claim of authority over beach cat sailing is bogus, imo.