What idiot does 90 MPH with 4 kids in the car? No doubt the roll over contributed to their deaths, but flat out agressive and illegal driving caused the accident.
I see this all the time, people who don't have a clue how to drive the "big" vehicle their penis envy required them to own.
You drive around in almost any SUV, whipping it around like its a honda civic or something.. taking it just to the limit of its suspensions ability to stay on the ground.. then sooner or later they take it just a little too far, and instead of a spinout, or other issue like a car would do, you wind up rolling the beast.
Having read this far it seems the rollover was due to impact and not to basic instability since there were long skid lines indicating a sideways slide; the vehicle is exhonerated IMO.