Turns out he got the Recipe: Flask of Distilled Wisdom instead, which is exactly the same thing (produces exactly the same potion), but is available for a mere 4 gold from the Cenarion Expedition quartermaster in Zangarmarsh. The only catch is that while both are BoE (which means they can both be sold on the AH), the Cenarion version requires that you be exalted with the Expedition to learn it. Which isn't super hard, but the fact is that players who are exalted can buy this recipe for 4g, and sell it on the AH to unsuspecting alchemists for hundreds of gold.
Of course, this scam has an expiration date, because as soon as word gets out that a) it's a scam, and b) the recipe is available for 4g in Zangarmarsh as long as you're exalted, the AH price will likely drop anyway. As Tobold says, Blizz could fix it by simply making the Zangarmarsh recipe BoP, but Blizzard probably thought they were doing players a favor by turning a rare drop into a rep reward. Anyway, if you happen to be shopping around for high level flask recipes, buyer beware.