Your comment suggests that Tesla's claims about the driver having his hands off the wheel for x seconds before a crash could be wrong. If the sensors detect the drivers hands are not on the wheel when they actually are on the wheel, then data logged about how long the driver's hands were off the wheel should be considered suspect.
I hope that's being investigated.
Personally, I'm having trouble believing the driver who died in the recent accident ignored the warnings for six seconds before the head-on collision, especially when he knew Autopilot didn't work well at that section of road.
I'm not familiar with how the system works. If the warning engages, is there a guarantee that the driver will have to take over shortly? Or are there scenarios when the warning turns off by itself and so the driver could have been waiting to see if the car would correct?
[Edit: lolc and Vik1ng pointed out that the warning isn't related to unsafe conditions as I implied. It's used whenever the sensors think the driver's hands are off the wheel.]