You seem to have misread the post. The data is encrypted using a key on the device. It is end-to-end encrypted. The key is encrypted on device and backed up to

You seem to have misread the post. The data is encrypted using a key on the device. It is end-to-end encrypted. The key is encrypted on device and backed up to Google and protected by a security chip that requires verification from the device to retrieve (unwrap the Titan encryption), which neither Google nor anybody else can pass because the security chip would lock them out after too many attempts. Even if they were to succeed in retrieving it, they would not be able to unwrap the device encryption of the key.