Again, the issue is that once you did share (= sent to) the data once with anyone, you don't have any technical control over what might happen to it (see the pi

Again, the issue is that once you did share (= sent to) the data once with anyone, you don't have any technical control over what might happen to it (see the pirate bay as an example). Quantum anti-tampering isn't going to help here, where it's your interlocutor that is the one that can't be trusted.