Not that it contradicts the point you are making, but the world (recorded) mile record for a 70 year old male is just under 5:20. (or 4:53 for the 1500m) http://www.world-masters-athletics.org/records/outdoor-men

(Irrelevant, but I added the 1500m time for people not familiar with mile times. But actually this mile record was set in the Netherlands, while the 1500m record was set in California. :P )