Reaction times ought to be one of the easiest things to fake. All it would take is a bunch of monitoring of large numbers of games to create a nice model of real player reaction times, which in all likelihood are normally distributed anyway.
Oh, right. I was thinking along the lines of 100m dash, where people often do have negative reaction times (which we penalize as false starts).
In poker we don't have much of an incentive to react instantly to any play.