This article is bollocks, though. It's a fit of highly unrepresentative data, not even a good one, but worse: it doesn't explain anything. If you take that model seriously, Usain Bolt could have been anybody in the entire history of mankind.
Seriously though, Allen is an instructor. These are educational pieces to bring a spark of understanding and creativity to students. I don’t think he is aspiring on modeling the absolute truth in these posts.
This piece has a learning about the working of non-normal distributions in sampling and reasoning about cut-off points.
No model is perfect, but I don’t have the slightest clue why you think that would follow.
Also, Ethiopian runners would be a counterargument. It's just reading way too much in a model that probably was there before the data. Seeing how everybody defends it as "learning", the example was sought to be described by the model.
Wat. His model says that many factors have to be perfect for someone to be as fast as Usain Bolt. If anything, it implies the opposite of what you said