I don't think it's sensible to say "responsible people rehome their dogs when they have children". Why would they do that - in case the dog attacks the child? By that logic, you'd be getting rid of your car too in case a crash kills them. I'm willing to bet all the money I have that far far more children per thousand population die in car crashes than they do from dog attacks.
OK, so the analogy is flawed because cars don't control themselves, but you see where I'm coming from.
I do feel immensely sorry for the SBT as a breed - it is, in my opinion, massively demonised by the media. Whenever a news story breaks about a "pitbull-type dog", you can bet your bottom dollar that the accompanying picture is of a SBT. It's a shame - there's a minority of idiots out there who use this breed as a weapon, or a show of force, and wrongly too because as has already been pointed out, they have been bred to be human-friendly. Bad breeding, bad training, bad ownership - that's what it boils down to. And bad laws that allow idiots to own these dogs in the first place.
By the way, I'm not commenting on this story in particular as I don't know the details of the owner, the situation in which the attack took place etc. But if an adult had to break in to rescue the child, then it's fair to say the child had been left alone with the dog - that's quite simply the first rule you do not ignore, no matter how soft your pet is.