I've been known to defend Toyota, so take this for what it's worth, but when I heard about this out of control Prius story my hunch was that it could possibly be a hoax or scam or operator error. It wasn't a model year that's involved in the recall, and the timing of it sounded weirdly on the nose. So close to all the hype about Toyota's recall problems.
Turns out that government officials can't duplicate the problem. This could mean any number of this and we all know the frustration of having a car problem, then, when you bring it back to the dealer for repairs, suddenly there's no problem. So the guy could be telling the truth.
Then again, there are a lot of people -- competitors, mainly -- who would love to see Toyota crash and burn. So who knows. But this particular story, even if true, is no reason to avoid previous model year Priuses.