I actually liked his explanation better:

"In that context, I made a further point: even denial of the Holocaust would not prove that a person is an anti-Semite. I presume that that point too is not subject to contention. Thus if a person ignorant of modern history were told of the Holocaust and refused to believe that humans are capable of such monstrous acts, we would not conclude that he is an anti-Semite. That suffices to establish the point at issue."

Indeed, if I were to write a letter to a paper saying that "Chomsky must be exterminated", would you say I did not call for his murder, because somebody who is ignorant of the fact the Chomsky is human could think that I was referring to cockroach?