I don't think the athletes have to renounce citizenship to play for another country. I don't think it is something I, personally would consider, but then again I am not good enough at any sport to play at the Olympic level.
Not many people have the opportunity to say: "I was an Olympic athlete." But if you CAN make the USA team, and you are US born and raised, then I don't understand playing under another flag....
Meh, that could have gone either way. The refs were right there and looking, so I will defer to their judgement on that one. They did seem to call things uniformly throughout the game.