Congratulations, you've committed a felony. That's what Doctorow's protesting: that Amazon forces you to commit a felony to do something as basic as changing a file format. He points this out in his Kickstarter:

What's more, Audible won't allow you to sell your audiobooks through their store unless you allow them to wrap your books in their DRM, which cannot be removed without committing a felony under Section 1201 of the Digital Millennium Copyright Act. Every audiobook you buy from Audible is locked to Amazon's platform...forever. They can revoke access to the book (they've done this with Kindle ebooks, starting with -- I shit you not -- George Orwell's Nineteen Eighty-Four... You can't make this stuff up!).