Some of the people on this board have been working on their PhD's for decades. So they'll be pleased to read this story: Postgraduate news and views: OAPs with PhDs. (OAP = Old Age Pensioner)
When I was at Fl.St.U. there were four graduate students in the doctoral program over the age of 70. I believe 2 completed. All the best!
I think that obtaining a Ph.D at that age is an excellent idea because it makes the person more marketable. When I hit 70, 80 or 90, a Ph.D might help me get hired somewhere. Even at 100.
All I can say is Hats off to the Old Chap . And it is fitting that he has the same initials as our own JB--John Bear!
I'll tell ya, with what's happening with social security, we may NEED to be marketable at 70, 80, or 90!