I very much appreciate you thoroughly addressing the concern I raised. From what I understand, the only potential threat from Posting Keys being available to others is that they could send encrypted messages as you, and the Posting Key being available to others already allows them to post unencrypted messages as you, anyway. Having your Posting Key would also allow them to change your public Quantum Encryption Key.

Is that a complete description of the potential ways an attacker could use your Posting Key?