MtGox does way more that just provide a platform for trading Bitcoins. They are also in the money transmission business according to their TOS. If I can copy and paste these terms so can an officer at the US DHS.
https://mtgox.com/terms_of_service.
PLATFORM TRANSACTION PROCESS FOR BITCOIN TRANSFER TRANSACTIONS
Members may at any time transfer any amount of Bitcoins to any other Members as well as any other Bitcoin users even if they are not Members (the “Transferee”).
Bitcoin Transfer Transactions may be initiated at any time from the following page:
https://mtgox.com/index.html. Transferees shall be identified by their bitcoin address.
Members shall be solely responsible for ensuring that any transfer of Bitcoins to a Transferee shall be a valid and legal transaction not infringing any laws including money-laundering laws and regulations.
Mt. Gox’s responsibility shall be limited to using reasonable technical efforts to ensure the receipt of the Bitcoins transferred. When conducting Bitcoin Transfer Transactions with a Bitcoin user who is not a Member, Mt. Gox’s responsibility shall be further limited to ensuring the transfer of the necessary technical data to the Bitcoin peer-to-peer network.
No Commission of any kind will be charged by Mt. Gox for Bitcoin Transfer Transactions.
PLATFORM TRANSACTION PROCESS FOR CURRENCY TRANSFER TRANSACTIONS
Members may at any time transfer any amount of currencies held on their Account to any other Members (the “Transferee”). Transfers to third parties who are not Members is not possible.
Currency Transfer Transactions may be initiated at any time from the following page:
https://mtgox.com/index.html. Transferees shall be identified by their Account name.
Members shall be solely responsible for ensuring that any transfer of currencies to a Transferee shall be a valid and legal transaction not infringing any laws including money-laundering laws and regulations.
Mt. Gox’s responsibility shall be limited to using reasonable technical efforts to ensure the receipt of the currencies transferred.
No Commission of any kind will be charged by Mt. Gox for Currency Transfer Transactions, except when the Account of the Transferee is set up in a currency different than the currency transferred (in which case the 2.5% Commission shall automatically apply).
I will leave it to reader to judge if Karpeles did lie after reading the above.