Now this is completely different on what you said earlier. From what I see regarding your concerns of rest each body part he works out has 72 hours of rest. Thats plenty of rest. I wouldn't advice someone who hasn't worked out in there entire life to do this but to work there way up. If he works out 45min a day than that is perfect. I do something similar 4-5 days a week. Throw that steroid stuff out the window. And the old pics I've seen from 50 he was never out of shape or skinny. He always had an athletic build. The mass will come from determination, eating right, and whey protein (if you are not getting the proteins properly).
regarding the 72 hours of rest, yes technically each body part is getting 72 hours of rest, but that isn't the issue, its the fact that your brain can only handle a certain amount of workload in a given period of time. Once you begin to overtrain your gains will not only stop but you will get weaker and smaller. After reading that he only does 45 min. a day it is more believable that this plan is working for him without steroids. He probably does a no BS compound type of workout that just hammers his muscle groups at a high intensity with a low volume which can prevent the overtraining. So as I said before, i dont want to go out and say that hes deff on steroids, id be overshooting it, but for the average guy, if they tried this routine with just average genes, it would more likely than not lead to minimal gains, even if they worked their way up to it.