Well, Mr. Hazell is communicating Maffetone's method. If you read the book (I did), then you'll see that Dr. Maffetone doesn't think the max heart rate chart (the one that's been around forever) is useful.

Also, the 180 formula is based on Dr. Maffetone's work and it is (ultimately) based on cortisol (which the body produces in response to physical stress) levels. He created a database by measuring heart rate against measured cortisol levels in thousands of runners. Heart rate (according to Maffetone) turns out to be a good proxy for cortisol levels, and that level corresponds very closely to age.

I'm not "arguing against" your question, I'm just relaying my understanding of the method.

BUT, if you're referring to that classic heart rate chart, the chart's creator said this:

"...The subjects were never meant to be a representative sample of the population, said Dr. Haskell, who is now a professor of medicine at Stanford. Most were under 55 and some were smokers or had heart disease."

Here's the article that contains the above passage (the article itself is from 2001, but I've never seen a better explanation of heart rate max history):

https://www.nytimes.com/2001/04/24/health/maximum-heart-rate-theory-is-challenged.html