If I understand it correctly, the whole scheme depends on Habeas's having bona fide claims for copyright and trademark infringement against unauthorized users of the haiku. I don't believe that that there are such claims. There are no copyright damages because there's no intrinsic market value to the haiku. (The haiku's use as a passphrase has nothing to do with the copyrightable content of the haiku; you could presumably use anything as the haiku.) There is no trademark because the haiku isn't being used to market a product or service.

Given the novelty of the scheme, I can't say for certain that a court wouldn't find a potentially valid legal claim here. But I would say the chances of that are no greater than 25%. And absent a high degree of certainty that the legal underpinnings of the scheme are sound, I don't think people are going to turn their e-mail infrastructure upside down to implement it.