As for the accuracy of his opinion, you might reconsider the all inclusive nature of yours.
Oh, I agree great accuracy has been obtained by lesser loads and that frequently. But I must say that neither is it correct in all instances. You have to take into consideration the bullet designs, mold manufactures and quality of lead used in making such bullets. I can imagine many cases were skirt expansion could fail to consistently occur with reduced (from originally specified, ie 60-65gr) loads.