Scott's arms may have become more mature and reached their full potential in size, but the arm shape would be the same as from birth. Unless he had extreme surgery to reconnect the muscle tendons, ligaments, etc to the arm bone. If you could/would change the basic muscle shape (again, location of the inserts attached to any bone structure) than most all the brothers would have great lower calfs rather than the higher up calf development some have (actually that higher type calf is built for leverage/speed). Any high peak or flat bicep is the genetic hand you were dealt. Always improve any muscle group beyond your dreams, but the basic shape will always be there. Kind of poorly misinformed or lacking in understand if thinking otherwise.
Any curling movement is a variation on a theme. A curl is a curl, twisting the wrist as the forearm is brought up to the contraction point close to the shoulder. Now if Scott got outstanding bicep development from doing Gironda type angle bench curls than that suited his bicep muscle inserts to take advantage of his full muscle building potential. But some other guy's may do the same exercise with the same intensity, reps and sets as Scott and have little to show for their efforts.
But if changing to a simple standing BB or EZ bar curl, these same guy's might gain outstanding results, taking advantage of their full muscle building potential. My own personal view is that more people have build great size and power with just those BB/EZ curls. But than again, I am into more of power BB'ing. Also adding (another personal view, that's all), the injury ratio could be higher on a Gironda/Scott/Preacher bench. Probably due to the full stretch some do, which is really not needed anyway, in that exercise. Good Luck.