What a sloppy article.
Correlation is not causation. All credibility is lost for this guy, in my view.
> We know from one study that people who played tennis a few times per week lived roughly 10 years longer than average. So we'll use that value going forward.
This is the study [0]. The study itself, in the conclusions, states that:
"Conclusion: Various sports are associated with markedly different improvements in life expectancy. Because this is an observational study, it remains uncertain whether this relationship is causal."
Has the author read the study at least?
[0]: https://www.zeiss.com/meditec/en/products/refractive-lasers/...