I have posted nothing on the article page as this would presumably be a Conflict of Interest, and have made here suggestions of the way in which the book may be used only because requested - my view remains that it should be done by an editor who does not have COI. I think that now we've moved on from the efforts to exclude a source through (wrong) application of the Notability guidelines we're left with Neutrality of Point of View as the main issue. Wikipedia reports what is out there and a decision to exclude entirely from an article an appropriate source which has a view on much that is in the article (as well as topics the article excludes) appears to be a bias. The idea that the only book of lit crit on Beedle the Bard has nothing whatsoever to add to an encyclopaedia article on the topic is incredible. I don't think COIN is central to the issue as it now stands; rather the central issue is NPV. I think there are wider issues which it would be interesting to discuss - for example had my username not been essentially my real name a post on the talk page a year ago saying "hi guys, this book exists and has something to say about the article" would not have generated this negative discussion. I suggest MedCab is a way forward because it can consider all issues, while COIN considers only one issue and probably one which is not central.