If you're instructing the driver to do something, and they don't, your last option is to fail as gracefully as possible (which is "what is the best path forward in the distance I need to stop at emergency braking rate + I must notify the vehicle behind me as soon as its clear I will take automated action, even if that's before I apply braking force").
Going off-road like it did seems safer than stopping on a highway. Sure there was damage, but far safer for the unconscious* occupants than being rear-ended.
(* I use "unconscious" because this guy was not paying attention, but also because it appeared to the car that the driver was dead)