I sort of doubt that any legal rights would be extended to vampires as a matter of course were they found out, so I'd side with Alicorn on this one. Turning and indoctrinating your own larger vamp police force on the sly would probably be more productive, but obviously also risky. Use fierce human rights activists? ;]
One could arrange to out vampires if they don't behave (including if the one threatening this is killed) and therefore call the collective wrath of the human military industrial complex upon them (see The Salvation War ;). Of course, this would require that most vamps would see the threat as credible and dangerous, and would co-operate in policing the unavoidable defectors efficiently enough for the blackmailer to be satisfied. This may be a tall order, and could lead to open war on follow-through.
In the vein of the Harry Potter and the Methods of Rationality discussion threads this is the place to discuss anything relating to Alicorn's Twilight fanfic Luminosity. The fanfic is also archived on Alicorn's own website <strike>(warning: white text on black background)</strike>.
Previous discussion is hidden so deeply within the first Methods of Rationality thread that it's difficult to find even if you already know it exists.
Similar to how Eliezer's fanfic popularizes material from his sequences Alicorn is using the insights from her Luminosity sequence.
Spoilers for the fanfic itself as well as the original novels need and should not be hidden, but spoiler protection still applies for any other works of fiction, except for Harry Potter and the Methods of Rationality chapters more than a week old so we can freely discuss similarities and differences.
EDIT: Post-ginormous-spoiler discussion should go to the second thread. (If you have any doubt on whether you have reached the spoiler in question you have not.)