You'd Think I Would Remember Not Writing a Book

So, apparently, there's some guy named Keir Graff who says HE wrote Cold Lessons:

Michael McCulloch is not just another talented first novelist. Yes, his debut crime novel, Cold Lessons (Five Star), is a hard-hitting roman noir, but McCulloch is more than he seems. Lurking behind the pseudonym is our own Keir Graff, Booklist Online’s Senior Editor.

You can read the whole story on Booklist Online. But who's to say that "Keir Graff" isn't a pseudonym for Michael McCulloch?