I thought that they dropped the nationality requirement because it just forced people to change their citizenship for their employer. It was simply too easy to work around the requirement.
More to the point... what does it matter?
Just watching the Olympics... the Canadian internet mogul guy jumped to Australia to board... I think he won a medal. The Japanese girl jumped to Russia to compete in pairs figure skating.... she needs a visa to go home to see her mom. I think I remember Navratolova represented the USA in the tennis Olympics.
Bottom line... it's not a big deal and I don't see how it builds support for a US flagged sailing team funded by a rich US owner... The modern Cup is not even as nationalistic as the Olympics.