From the article:

Amazon says that that the books in question were added to its catalog using the company's self-service platform by a third-party who did not have the rights to the books. And it says it will no longer delete books in this manner.

When we were notified of this by the rights holder, we removed the illegal copies from our systems and from customers' devices, and refunded customers. We are changing our systems so that in the future we will not remove books from customers' devices in these circumstances.