Exactly------------Mr Williams had little or no hair, and was wearing a bright plaid shirt that day! And besides, who cares about a 20-year-old man being mistaken for a wrinkled man in his fifties? Happens all the time!
Rowland makes it clear he didn't pay much attention to the man in the SN and his description must be viewed in that light.
He describes a black male who is very thin which comfortably describes BRW
He describes him as " bald or practically bald, very thin hair if he wasn't bald". BRW had a very high forehead and quite close cropped hair. Viewed from a distance, looking upwards with a dark background I think it's not beyond the realms of possibility BRW could appear 'practically bald':
He describes him as wearing "a plaid shirt. I think it was red and green, very bright color". This is a reach but as we know he was wearing a green shirt and was also eating a bag of Fritos, a very bright red colour. I can see him holding the bag up in front of himself as he eats them and we know he finished them off (I believe Studebaker mentions Frito crumbs in the sack but I don't know what happened to the bag). Rowland, not paying much attention sees the bright colours held up in front of BRW and thinks it's part of the shirt.
As for his age, Rowland seems pretty sure he's quite elderly but he does say this:" Seemed like his face was either--I can't recall detail but it was either very wrinkled or marked in some way." It was marked in some way - BRW had a moustache!
He also notes, when asked about the age of the man with the rifle, that his estimation "could be obscured because of the distance," which he estimates as 150 to 175 feet.
Finally, he describes the man in the SN as being "fairly dark, not real dark compared to some Negroes, but fairly dark".
Rowland's observations have to be taken in the context of the distance, the elevation and, as he says himself, he wasn't really paying that much attention to the man in the SN. His description shouldn't be held as 100% accurate.