Yes, but I suspect this breeder doesn’t have any dogs with a good line. Reputable breeders don’t - well, they don’t do anything we read about in this story.
I wonder if the druggies, white trash and gangsta-wannabes have started breeding mastiffs for aggression like they did with pit bulls? Almost a separate breed by now, the bad rep comes from there. An unstable, highly aggressive mastiff inbred for generations to fix those traits would be a terror.