You misunderstand. Apple can't unlock the phone with the signing keys, all they can do is make it easier to brute-force the passcode. If this person had used a

You misunderstand. Apple can't unlock the phone with the signing keys, all they can do is make it easier to brute-force the passcode. If this person had used a long passphrase instead of a 4-digit code, even this software hack wouldn't help.