Wrong. The certificates state something to effect of "this certificate may not be bought, sold, or bartered". I can't recall anything that says "only the original owner of this certificate is subject to these restrictions". Everyone in the chain is guilty of violating the rules - the original owner, all the intermediate buyers/sellers, and the final buyer. Anyone in the chain could legitimately have their MP account frozen or closed, and the final buyer can also be forced to purchase a full-fare ticket.