That wasn't a loophole, what that event was doing was open and naked gender discrimination and their ban on men was legally unenforceable. The law was on their side. What women should do in retaliation is bum rush those men's clubs where all the power decisions are made by the top 1% of men. Fun fact the dean of my uni's computer science dept was a woman, and decades later it still is. THEY have a crucial role in recruiting women students, it begins at the start of the pipeline.