I did not interpret their comment that way. That would be unreasonable, however their comment included mention of physical break distance, so I'm pretty certain they didn't mean actual human response time and instead how long it takes for a human to respond and slow the car, which is the metric of interest here. Even for a robot with millisecond response times, you will be breaking in the multiples of seconds, not instantaneously. Observation "reaction time" really is completely irrelevant here.