Touring is hard! I've done tours before and it's exhausting. Granted not in the same luxury as mark, I can only imagine even in luxury conditions, at the age of 70 it would be absolutely draining. Marks (i'm guessing) back problems also would make the shows pretty exhausting. Surely he would be on pain meds not to mention physio therapy? Even doing 3 gigs a week and driving 20 minutes from my house i'm pretty tired by the end of those nights and i'm half the age of mark.
He keeps the setlist static to play to his strengths and keep it predictable. He has to shorten the set sometimes when he's not feeling up to it. I think that's perfectly justified.