It would appear that he is: Zachary X. Hruby...
"Mel Gibson’s movie “Apocalypto,” which opened Dec. 8, gets a thumbs down from University of California, Riverside Maya scholar Zachary X. Hruby, who was asked to pre-screen the movie by National Geographic."
Be suspicious of anyone with an X in their name. He is just another apologist/revisionist hiding behind credentials.