Holocaust denial is one of the most insidious forms of hate speech. It targets a religious group in that it is based on the claim that either the Holocaust never happened, or that it was exaggerated by Jews in order to advance their own political and economic interests. Evidence of the Holocaust is well documented. Most people who join a Holocaust Denial or Holohoax group are not there to have an honest debate regarding its occurrence, or to study history. That is a pretext. Rather, they are there to distort the truth, to push an agenda of anti-Semitism, and to find like-minded people.
Facebook is a private company with terms of service to which all of its members agreed. Facebook has set its own standards regarding allowable forms of speech on its site and has banned many types of speech that may otherwise be allowed under the first amendment of the U.S. Constitution. Facebook does not allow pictures of nudity or graphic violence, comments that harass, annoy, or target an individual, or hate speech. The latter includes comments that target an ethnic, racial or religious group.
Therefore, by its own standards, and in keeping with the majority of international opinion where in many countries Holocaust Denial is a crime, Facebook can and should ban Holocaust Denial pages and groups as a form of hate speech.