In all wrecks the driver is at fault but who's the driver when the autopilot is on? Sure the person in the driver seat can turn it on and off but are they truly in control of the vehicle when it's on and their hands and feet are off the steering wheel and peddles or is Tesla in control?
Who's ever in control of the vehicle at the time of the crash is to blame for the crash so I tend to agree with the NTSB on this one.
The owner should have been paying attention to his surroundings instead of sleeping. All he had to do was brake (bringing the car out of autopilot) and allow the truck to merge. You cannot blame Tesla for his own negligence.