Dogs don't reason? You deserve a treat for that brilliant insight.
my point, that an educated, competent dog handler would most likely have been able to predict the dogs behavior and take adequate measures to prevent the outcome
"Educated" and "competent dog handler" aren't in the lexicon when it comes to typical pit bull owners.
And "most likely" doesn't cut it anyway when it comes to behaviors that are lethal or injurious to innocent little children.
Euthanizing that vicious dog is the best way to ensure the ability to predict it's future behavior.
Perhaps that's true in the circles in which you move. I personally choose to associate with a better class of people.