That study doesn't purport to be an objective measurement of absolute reaction time. It's comparing relative driver behavior between a driving simulator and a test track, and it doesn't seem to have controlled how immediately drivers needed to respond to avoid a collision. It does, however, include one objective measurement of human reaction time, albeit not as a primary result of the study:

> the time from incursion start to throttle release included the reaction time of the tow vehicle driver pulling the foam car (which was consistently less than 200 milliseconds)