Hmm. Good point. I bet the resistance itself doesn't pay that much attention to his age, given the combination of (a) a high (and fatal) turn-over rate, so that he's impressive just for surviving a couple of years, and (b) the presence of other aliens who aren't all that aware of a human's life expectancy or healing capacity.

On the other hand, the Predator society clearly does know a fair bit about humanity, so they're probably incredibly freaked out by this human who continues to head the resistance.

I bet MacLeod thinks Royce is extra-terrestrial. Or possibly an inheritable title. And then at some point he meets Methos.