I know someone with a scar on their face from being attacked by a Chihuahua. Does that meet your criteria for "maimed for life?" Disfigurement from an injury is worth a lot of cash in court, so I think it meets the threshold.Yes, maybe chihuahuas are more aggressive and bite more, but nobody has died or been maimed for life by a chihuahua. Coming to the conclusion that therefore pit bulls as a breed are not aggressive or dangerous is faulty reasoning.
More to the point, no one that I've seen (or read here) is making a conclusion that pit bulls are not aggressive, only that they are not the only ones who are. In fact no one is making any claims or showing any evidence that any dogs do any thing "as a breed." THAT would be faulty reasoning, as it is easily disputed by producing a single dog within a breed who is clam. Instead what has been laid out is that you can find aggressiveness as a trait in any dog, regardless of breed, and it seems to be more a factor to do with improper breeding practices (perhsps lack of any practice) or the way the individual dog is socialized or raised.
I mentioned I had a Rottie who never bit anyone his whole life. That dog's father belonged to the mom of a Navy LT I once worked for, and her dog killed a man (silently) who attempted to burglarize their home. She came downstairs in the morning to find a body with no throat left laying in a pool of blood in her living room. If it were only a matter of genetics, I should have expected my dog to be more aggressive, perhaps even to have viciously attacked that unwanted solicitor who bothered my wife - but he never did much more than bark at anyone. He would tear his dog toys to shreds, but not humans, and I think it has to do with how we treated him as a pup, not letting him get too much control. Not scientific analysis perhaps but a reasonable theory.
In the matter at hand in the OP, the dog had already attacked, so academic discussions about breed characteristics are irrelevant. If it was my son attacked, the dog would have been dispatched forthwith.