[Quoth]

The only anti-piracy Amazon should be concerned with is books or products published dishonestly on their own site. Elsewhere is none of their business, unless they are owning the copyright.

Edit:
Indeed the Mary-Sue article states issues and amazingly fails to conclude that the issue is the Exclusivity clause. They seem ignorant of how easy piracy is. Copying ANY system of DRM to a DRM free version is trivial. The only anti-piracy that works is government law enforcement closing the operators. Even that can't eradicate piracy.
Amazon can't stop content on their site being pirated. The conclusions of the article are delusional.

Amazon are treating the KU content as if they own the Copyright and that somehow the content providers to them are doing the piracy. Both of those are wrong.