Just out of curiosity......was this said jokingly, or were you serious? On the internet, its often hard to tell if someone is speaking tongue-in-cheek or from the heart.
Certainly all wild animals should be respected. When humans are interacting, they need to exhibit a large degree of care to ensure not only our own safety, but also that of the animal. I would demonstrate the same amount of care around a cat or a dog of whom I am unfamiliar with their temperment. I have also been the recipient of a good scratch or bite from a certain fluffy feline whom I know like the back of my hand.....because she's an animal. And well, sometimes (gasp!) she acts like one. In her OWN DEFENCES. Not necessarily to "attack" or with the intent to purposely harm.
I honestly don't believe that the dolphins in the SW feeding pool are simply vicious killers waiting to snag their next victim when the unwitting human inadvertently waives an empty fish tray in the air. I think that poor dolphin was as excited as the little girl and took the opportunity to snatch at the tray in search of more fish. I think that dolphin was guilty of being a glutton, but not of a vicious attack.
Can they (or would they) kill in other circumstances? I have no doubt. But in this controlled habitat? I cannot think that SW would put ANY dolphin in that situation that has exhibited aggressive behaviour. It would be senseless for them to set themselves up for that kind of liability.
Dolphins have much more reason to fear vicious humans than the other way around, IMHO. Our species seems to be the more dangerous of the two.