There's a good chance that the people described in it are no longer with us.

Aside from my own age (I'll soon be 75} I have  lots of experience with seniors having sex:  I limit my practice to people at least 65 (with the exception of some of my patients who suffer from chronic diseases.) and the average age is the ate 80s. I also have a small practice and each physician in my group has only a few hundred patients. (The average Geriatrician has 2500 patients, the average internist has 5000; so a few hundred is a rare privilege and we get know our patients extremely well)
In the psst there or four years, I have had at least five patients over 85, including three over 90, marry someone of their age.  In each case the couple hand not had sex in years and in most cases decades  I met with each couple many times to discuss: viagra vs challis; lubrication, safety, positions etc. In each case the couples start to have sex and three of these couples are having very frequent and passionate sex.   One couple had to wait for clearance from the Church because he is a Catholic Deacon and --I didn't know this-- unmarried or widowed deacons cannot marry without special dispensation. They waited over a year and had no sex during this period until they could not bear it any longer and they just got married and began having what seems to be great sex.  
I guess we should all take heart from these folks who are clearly having great sex in their late 80s and their 90s.  
It is like my younger wife often tells me: "75 is the new 45.

I am 52.  have hooked up with women in their late 60s & early 70s.  some great pussy out their