The trouble with your analysis is that MS CAN be VERY debilitating one day - then three days later you could be playing tennis. You can't take "he got around all week like a 16 year old" and extrapolate this into what he is like all of the time. When MS hits, it can knock you WAAAAY down. Her parents may have been there during his "good" days.
Or, maybe he WAS in the middle of an attack and had smoked a joint and it was working very well.....;-)
MS does hold the distinction of "most researched" when it comes to medical marijuana.