Did Larry Pratt say he doesn't believe the Holocaust happened?
Not that I am aware of, but people as smart as Pratt usually check out where they will be speaking.
I would put it to you this way; If someone you did not like was doing the same thing as Pratt I would guess you would not ask that question.
Further research shows Pratt having been involved in other ways with this sort of stuff.
Will post the links when I get a chance.