Einstein, much as he was without a doubt the greatest Physicist in our history as a species, once said that there was not enough Uranium on the planet to build a nuclear weapon. There are others more deserving of this "accolade" if you truly believe it can called that. Oppenheimer is certainly among them.
I don't see a problem with Einstein being referred to as an American, but I would have imagined that having him as a German SGL would have made more sense. His most important work (I'm a Physicist and trust me it was General Relativity by far) wasn't done in America. He was American for only a small fraction of his life.
Feynman was a fantastic Physicist (I'm drawing Feynman diagrams in one of my courses at the moment), but I don't think he can be compared to Einstein. They actually dug up Einsteins body to see if his brain was abnormal, now that is an accolade.
Did Prof. Stephen Hawking make it as an English SGL? It would be weird to have someone alive in the game.