NO, this cannot be true. Makes absolutely NO difference how old a buck is when he breeds. A buck at 1.5 will pass exactly the same genetics on as he would when he is 2.5 or 3.5. Just as a human father would pass his same genetics on whether he fathers a child at 19 or at 40. Alt was making up "trophy hunter" biological theory here.
The difference is we are not talking about the age or genetics of an individual buck, we are talking about the average genetic makeup of the entire buck population that are doing the breeding and there is no question that ARs protect the bucks with the poorest genetics for the rate of antler development. Prior to ARs, 18% 0f our 2.5+ buck wouldn't have been AR legal with the 3 pt. AR. Now it is likely that 20-25% of our 2.5+ buck are protected. Therefore, the vast majority of 3.5 buck available to become dominant breeders are those buck ARs protected because those bucks had inferior genes for the rate of antler development.