Who cares if he had 5 seconds to see the barrier if he only had 0.5 seconds to realize that the car went into casual murder mode right as it veers into the barrier. They make it sound like it had to have been driver error with facts that are irrelevant to the question at hand. Your assumption that Tesla claimed he didn't have his hands on the wheel at the time of the accident is exactly what I'm talking about, Tesla's PR release is filled with weasel words to do exactly that.
I'm not even trying to suggest that Autopilot is less safe than an alert human driver, but one thing is clear, we certainly can't trust Tesla to determine how safe it is.