Exactly my line of thought. Morrison has done as much work with the Joker as he has done Batman over the course of his run, and Didio said there'd be a unified approach to using him following RIP - Meaning this. Morrison has an idea for him, therefore he's out of bounds for now, which is undoubtedly better than pre-RIP, where Joker gets messed up and scarred but still appears normal in every other book.