It's clearly stated in Kickstarter's TOS that pornographic material is not allowed to be sold. Yes, some companies have gotten away with it by being coy with their wording, but the last thing we want is someone reporting the campaign and getting it shut down. And that's not to mention the other reasons we listed, which would still be applicable even if adult items were allowed on Kickstarter.
We have gotten the a-okay for a standalone 18+ digital version though, and we'll be updating the Tumblr post with that information soon (when I get a free moment from all this launch hullabaloo).