The article says the dog was adopted from an animal control facility. Those are not reputable animal shelters. Animal shelters thoroughly screen the animal they take in. Among other things, they test for temperament. Animal control facilities don’t bother with that. If you take in an animal from animal control, it’s buyer beware.
I don’t know how it works in Tennessee, but I am aware of places where animal control facilities are indeed reputable and thoroughly screen animals. I suspect nomenclature differs from place to place.