Seems iBA has been updated with a clearer EULA with this at the top:
If you want to charge a fee for a work that includes files in the .ibooks format generated using iBooks Author, you may only sell or distribute such work through Apple, and such distribution will be subject to a separate agreement with Apple. This restriction does not apply to the content of such works when distributed in a form that does not include files in the .ibooks format.
Thank you, and good night. I’ll be over here, radiating smug.