Then it's a good match for Arnold Rowland's eyesight.
Yes, only so much detail can be discerned from the distance Arnold Rowland was from the TSBD. Even he indicated the distance prevented him from being able to identify the man with the rifle. Here's a relative close up from professional photographer Dillard. And, to me BRW looks older than he really was. Also, consider that Arnold Rowland was only 18-years old on 11/22/63. To a teenager, "elderly" is quite different to what a middle-aged person would consider elderly.
I can see how Arnold Rowland (from his distance to the TSBD) might describe BRW as appearing elderly.