I actually think Kevin's story makes some sense.  I still think he should return the BTC he withdrew (or forfeit the $3000 and all remaining BTC in account to cover the loss, which, as he claims, is probably worth close to $10,000 at market prices).

Kevin says (1) he has a higher withdraw limit than $1000 and (2) he withdrew around 600 BTC.  It is true that his post implies that his limit was at $1000 when he withdrew, but I don't think that's actually the case and I don't think that he meant to imply that.  Many on the forums have claimed that the BTC withdrawal is based on a 24-hr rolling average (people who claim to have hit this limit themselves, presumably when trying to withdraw during recent volatile periods) and not on the current market price.  At that point the 24-hr rolling average was apparently around $4.5, which would have allowed a maximum withdrawal of around 200 BTC per $1000 allowed.  600 BTC withdrawal, then, aligns with a roughly $3000 withdrawal limit.  I think perhaps he assumed that the limit was based on $0.01, but was in fact wrong about that.

But, like I said, I still think he has no claim to profit on the buy-side of a fraudulent sell order.