Hm, that's strange, because I seem to recall Chomsky saying something to the effect that 'even to enter into the arena of debate about whether or not the Holocaust took place is already to have lost one's humanity."
I believe the statement you are referring to came from Chomsky's argument that if a person denies the Holocaust that person should not therefore go to prison. Furthermore, as it is important to protect the freedom of academic inquiry (even ridiculous inquiry such as denying the Holocaust) it is important to acknowledge that questioning the historical validity of a claim of genocide does not necessarily indicate a prejudice of the inquirer against the group making the claim. That is, in theory, one could have crackpot reasons for doubting the Holocaust without also being an anti-Semite. I happen to agree with that.
However, assuming that I accept this phrase outside of its original context, and dropping everything that I know about Chomsky (who was raised Jewish, and whose father was a Hebrew school teacher), I think it's pretty obvious that denying the Holocaust usually indicates anti-Semitism.