No, there’s no doubt in my mind that the median age of a president is greater than the median age of the general population, but that in no way implies that old

No, there’s no doubt in my mind that the median age of a president is greater than the median age of the general population, but that in no way implies that old age “runs deep” among presidents, which I take to mean that it’s a common thing. About half are less than 55 and half are more than 55. Most are somewhere near 55 (since the distribution conforms to a bell curve). 55, in my opinion, is not “old age”, but your mileage may vary.