I do think it's wrong that the dog had puppies so late, but I think perhaps there's a better way to go about educating people. I DO believe that her dog could have been depressed, in which case suggesting a behaviorist or meds would be a good solution. It does seem odd that her dog was completely inactive for years and after having puppies was lively enough to play with other dogs. It didn't sound to me like she was dragging herself around just to care for her puppies, but that she was more active in general. That does sound to me like she was happier and I do think it's possible that some kind of hormones or chemical changes from being pregnant could have caused that. BUT, the same effect could be achieved with antidepressants without adding to the pet overpopulation from a dog that isn't breeding quality, wasn't supposed to be bred, and way to old to have a litter.
Anyway, my only point is that I think gently educating people is much better than admonishing them. It doesn't do any good if they go on the defensive and don't listen to anything you say.