At rest, the optimal whey protein dose for non-frail older adults to consume, to increase myofibrillar MPS above fasting rates, was 20 g. Resistance exercise increases MPS in the elderly at all protein doses, but to a greater extent with 40 g of whey ingestion. These data suggest that, in contrast to younger adults, in whom post-exercise rates of MPS are saturated with 20 g of protein, exercised muscles of older adults respond to higher protein doses.

That is a quote from the study you refer to. It clearly states that 20g casused stauration for younger adults, yet the older adults responded better toa 40g dose. So, young people need less protein to boost synthesis, while older adults benefit from more protein.

This study contradicts everything on this page. Thirty-seven elderly men (age 71 (sd 4) years), saw a significant muscle protein synthesis increase from 20 to 40 grams.

If 71 year old men see a difference, you can bet younger, higher testosterone men would see an even bigger difference and would benefit from 50, even 60 grams.