I agree that the probation thread is applicable to this situation. I feel sympathy for Yannis for whatever his personal situation is but it doesn't seem to be any kind of excuse for what happened. If he had a valid excuse for not completing his transaction with Matt, then he shouldn't have been able to sell it to anyone.
Oh, and a couple of people have been real jerks toward Matt. Matt has handled the situation well, we need more like him. He's alerted the forum to a bad seller and while I think Yannis should be put on probation, it's Matt's call.