1) you are right. There is no simple solution, One good policy would be for a first step, the free version of DASH to support only documentation for libraries with GPL license.
2) I do have a serious problem with their business model. Reselling their app after new version. I don't like that business model.
2. Dash was pulled from the App Store due to conflict between Kapeli and Apple. See the links in the comments above for details.