In order to "seize" ownership of bitcoins, the FBI would need to gain access to his private bitcoin keys. Wouldn't it be possible to transfer all his bitcoin to

In order to "seize" ownership of bitcoins, the FBI would need to gain access to his private bitcoin keys. Wouldn't it be possible to transfer all his bitcoin to a different address with a private key that's encrypted? Wouldn't such an action prevent a seizure? EDIT: That's what appears to have happened.