I think people look at this sort of thing the wrong way. The concern isn't the likelihood that an animal will resort to instinctive behavior, but rather the animal's propensity for carnage should it occur. I'm not sure what the difference is between owning one of these cats and a pit bull. They both pose a slight risk of going primeval on your ass, and should they choose to do so, they're both going to make a very ugly mess of you in short order. I don't think pit bulls are inherently dangerous animals. They're intensely loyal and unlikely to go off the reservation. My stepbrother's pit bull and I are fairly close. I like her, she's fond of me, and if the shit were to hit the fan there's nobody in the world I'd rather have on my side than that dog. I'm mindful of her potential for carnage, though. I'm aware of two different ways of shutting her down should the need arise. I think this is exactly the same way I'd view Messi. Lovely pet. Fun to be around. Amazingly loyal. Greater element of risk than, say, a snauzer or a lab. Something you should probably be mindful of.
I get what you're saying but I don't think the Pit Bull comparison is a very good one and the reason is there is a MASSIVE difference between a domesticated pet and a wild animal. Pit Bull or not, a domesticated pet was far, far less likely to maul someone out of the blue. Wild animals on the other hand can be set off by some of the most mundane shit you can imagine.
Domestication is not binary.
While all dogs are domesticated to a degree, they've essentially been bread to be our pals, they still retain the basic instincts that they've been instilled with. A golden retriever that has never even caught wind of a sheep before has an instinctive knowledge of herding. The same applies to your bull terrier family of dogs, which has been bred to kill pests and engage in sport. We just don't pay so much attention to the former because nobody cares if your shelty starts herding the kids around the house.
On the flip side, both of those cougars were fairly well domesticated, as well. One was rescued from a zoo, and the other was orphaned and bottle raised by the owners. While the instincts are still there, I don't gather that either one has the foggiest clue what it's like to live in the wild. Humans, I would guess, are all they've ever known.
In general you may be correct, but given the circumstances with the two cougars, I'd say they're very similar.