I thought about doing that, but it would mean sifting through the US. If Serbia or Bosnia or Macedonia had won medals, I would not have included them in Austria, and I mentioned vetting Amy Williams to make sure she was from Roman Britain, but doing all that for the USA would be too complex.
This was strictly geographical, as the Croats & Slovenes & Franks & Angles for whom those countries are currently named were no part of the Roman Empire. Therefore, I would have had to check all the US athletes to make sure they came from the former British parts of the country. Why should they get credit for medals won by Californians because California would later be conquered by a people that hated them so much they picked two wars against the British Empire?