Read the Tenure Committee's explanation why:
Perhaps most disturbing, however, are the statements that come directly from Dr. Jones's mouth. Several faculty members maintain that Dr. Jones informed them on multiple occasions of having discovered the Ark of the Covenant, magic diamond rocks, and the Holy Grail! When asked to provide evidence for such claims, he purportedly replied that he was "kind of immortal" and/or muttered derogatory statements about the "bureaucratic fools" running the U.S. government.
Hat tip: Glenn Reynolds.