What a load of crap. Their jaws do not lock. They are tenacious and will hold on in a fighting situation but they release on command. I have never or never would condon dog-fighting but I have studied it in order to know my enemy. During the period when dog-fighting was semi-respectable if a dog did not release at the handlers command or worse turned on his handler when the handler was separating the dogs he would be put down. The point that the media and others are either ignorant of or deliberately avoiding of is that pits and related breeds were bred to be docile to humans.
Unfortunately there are creatures that twist the pits natural tendencies and train them to be human aggressive.