I've seen these around town, mostly on the College/Carlton leg of my ride, I usually give them a wide berth and pass - as others have said they're not able to hold a good pace for too long.

Sounds like the person riding it was a dingus, this happens anywhere - at least he wasn't "playing" in a 2000lb car - steer clear/give space to them and just let them get all peeved off, no reason to let him spoil your ride/day