Smart thinking on the kid’s part to use his belt as a leash plus he took a gamble on his own safety to save the man. My wife and her dog were attacked by a pitbull and a woman delivering papers saved her by opening a rear door and screamed at my wife to jump in the car...
I view the problem coming more from the owners than the breed. Any dog can be trained to attack.
I know a lot of people disagree, but I was raised with a registered boxer that was trained to attack on command. He didn’t back down from anything that he viewed as a threat to his family (us).