Common sense can be false.
I remember before I began running a couple of years ago I read research about runners and knee injuries. And it turns out that you're more likely to get injuries if you run less than 4 times a week OR run more than 4 times a week, the sweet spot is to run about 4 times a week (approximate number as I don't remember what study it was). The reason being that if you run about 4 times a week the body creates various protective tissues around the knee that helps protects it. (or something like that I don't remember what study it was). If you run less than that the body doesn't create enough, and if you run more the body is prone to fatigue, etc.
But anyway, that really surprised me and it made me realize that common sense isn't always right. You have to look at the study and see it for yourself. And since we don't have the data/studies that he's looking at it's unfair to say that he's ignorant IMO.