He is definitely an outlier in terms of good physical health compared to other 53 year olds (or any age for that matter).
A couple of things to note:
- He has been a vegan for 20 years but been training for 45 years. He ate whole animal proteins for 25 years while training. How much muscle mass did he have when he became a vegan? Probably no more than he has now (although he could be leaner now).
- He is very ripped. He also looks to be about 150-160 pounds max.
- Amino acids are essential for synthesising new muscle tissue. However many overestimate how much protein is actually required. When calories from carbs and fat are adequate, the amino acid requirement to create new muscle tissue and repair damaged muscle tissue is reduced.