Wow, for 50 Dr. Sinclair looks excellent.
He's still only 50, though.
I don't think he looks fine for someone promoting a diet for optimal health and longevity. If a layman, then he would look average or slightly below.
Here are other personalities for comparison.
Mark Sisson, a promoter of the paleolithic diet at age 65:
Neal Barnard, promoter of a plant-based vegan diet, aged 65:
Dr. Peat, promoter of the transcendent Over-man diet at the age of
82:
Loren Cordain, advocate of the paleolithic diet, aged 68:
President Bill Clinton; consumer of the bean-vegetable-and-fruit diet; enlisted recruit on the starship Enterprise at the age of 72:
President Donald Trump at the age of 72; favorite bedtime snack is steak and ice cream.
Those who eat a plant-based diet have apparent skin inelasticity and a sunken, gaunt appearance.