I'm doing my best to track this conversation, but it's a bit over my head. So say the key cannot be read. What is to prevent Apple from delivering an iMessage s

I'm doing my best to track this conversation, but it's a bit over my head. So say the key cannot be read. What is to prevent Apple from delivering an iMessage software update which just POSTs each message to api.nsa.gov/warrants? If I can copy-paste an iMessage, it's getting turned into plain text at some point...