That would rule out autopilot entirely, wouldn't it? If true then this is just a case of someone falling asleep behind the wheel that could happen in any car. But with modern safety features like lane departure avoidance and automatic emergency braking. Tesla's active safety features can even brake for stop signs and traffic lights in addition to cars and pedestrians. And regenerative braking will bring the car to a stop much more quickly than a gas car when the accelerator is not pressed.
I'm trying to think of weird edge cases, but yeah it does seem like the odds are against AP being on in this case. Maybe TACC was on, but even that seems a little inconsistent with the report.