His philosophy is that Strength is Everything, so cutting weight or limiting calorie intake for "lean gains" limits the muscle mass (and strength) you could be gaining.

It all depends on your goals.

It's certainly valid for him to value strength above everthing else. But most of us don't, most are more interested in longevity and quality of life during those years. And so it raises the question if his lifestyle is good in those aspects or not.