It is a fallacy to assume that because private keys have been leaked in the past, private keys will necessarily be leaked in the future.
Remember, the DRM-can-never-work argument doesn't apply here. DRM-can-never-work is that the user must be supplied the decryption key with the encrypted content. That does not apply to signing; you must be supplied the public key, but the private can be held private.
Remember, the DRM-can-never-work argument doesn't apply here. DRM-can-never-work is that the user must be supplied the decryption key with the encrypted content. That does not apply to signing; you must be supplied the public key, but the private can be held private.