To confirm the ownership of bitcoins, one must create a message signed by the private keymust create a message signed by the private key of the Bitcoin address, with a message in context. If the message is unique enough, such as a full sentence or paragraph that is relevant and Mt. Gox acknowledges it publicly through their website or other means, one can sufficiently conclude that they do have private keys to an address they signed with.
None such such message exists for the "finding", nor have they publicly admitted to ownership. All claims of "finding" is pure speculation.
