Yeah, well how much can he bench press?
What he's doing is amazing, but at the same time, I can bet some people are going to think "the dude's gotten to be 100 and running is the cause of it along with his diet" or words to that effect.
It's genetics, first and foremost, and then what you eat and how you work out--if you work out at all.
Jack LaLanne, the ironman of strength and endurance, died at 97. He swam up to two hours a day, lifted weights, and ate healthy food most of his life.
His brother died at the age of 96 (I think) and didn't do much exercise outside of walking and playing golf. I don't think he was a vegetarian, either.
JMO on all this. The dude, though, IS amazing.