Yup, he's got it right. Same angular velocity (degrees / second) but the bigger the diameter, the faster the linear velocity. (ft / second) The feathers on a larger diameter shaft are traveling a further distance in one revolution.
Also, assuming all things are equivilent as far as starightness of the arrow, and the distributed weight / total weight of the arrow, a larger diameter shaft will have more rotational torque applied to it in comparison with a more skinny shaft. (also assuming the fletchings are identical in every way between the two arrows)