It's not about whether Meb is American or not. His citizenship is almost as irrefutable as Obama's. However:
What are the odds that he'd have a genetic profile advantageous to distance running if he had been born to two random Americans?
Fact: Worse than being born into a demographic that have been evolving at altitude ever since our species first emerged in the region.
Would he have been as successful if he hadn't grown up at altitude, say, like an average American, in America?
Fact: Growing up at altitude is an enormous advantage. While Hall has that advantage over most of the world, so does Meb. The difference? Eritreans are more likely to be born at altitude than Americans. It's a simple matter of topography.
Do these facts make Meb less relate able to the hundreds of millions of Americas who grew up close to sea level and have physiques (even when in shape) that lend better to the shot put than the chicago marathon?
East Africans are the Yankees of professional running. The rest are the Cubs.