Maybe it's just me, but I took the original concern to be for people and objects outside the car. It's a bit jarring for your only concern to be the passengers.
It's an argument against using some irrelevant momentum number in a comment. Without showing this momentum number, their comment is just "I'd say it's gross negligence to drive that fast at all on any surface street with sidewalks, traffic lights, intersections, stores, whether the driver is asleep at the wheel or not, autopilot or not, drugged or not" which certainly wouldn't get as much engagement on HN.