AIUI the spec being leaked ironically makes things worse, because for an unofficial implementation to be legally kosher it would have to be clean-room reverse engineered anyway, and since the official spec is out there the integrity of such an effort would be called into doubt. You'd somehow have to prove you didn't look at it, ever, or at least be trusted enough for people to take your word for it.
(I'm not a lawyer, please correct me if I'm wrong)
(I'm not a lawyer, please correct me if I'm wrong)