Sure you can deny what didn't exist in the first place. That's basic decision theory in statistics. The null hypothesis is that the holocaust did occur. You ware trying to convince people to reject the null hypothesis and they are demanding that you supply them with sufficient evidence to avoid type I error with 99% confidence.

WW II is still in living memory for some people and the winners of wars right the history books. I don't think anyone will have a really accurate picture of what went on in NAZI Germany for the next 100 years. It will be left to future generations to sort out the fact from the propaganda.