At the moment, Blizzard works to protect the most the people who give them 20$ for the token, and ensure they always get a good amount of gold for their token while still getting it sold within reasonable timeframe. I imagine most people who sell token to get gold don't want to bother with wow economy intricacies (otherwise they would have gold from playing the economy game and wouldn't need to buy it), so it's a wise move to protect them from scammers, undercutting wars, wanna-be-monopolists, TSM snipers and all the stuff they didn't want to deal with in the first place so they decided to buy gold.
For Blizzard, the most important customer is the person that buys the token for 20$, so the system is built in a way to protect them more than the people who sink gold into tokens on the other end.