The answer is obviously no, but this thread is way too boring if I say what I think, so I am going to say the opposite.

Lets look at the facts. The holocaust happened. I mean, it really, really obviously happened.

Why might someone deny that fact?

1) they are ignorant of the evidence for the holocaust. Well, OK. Personally, before rushing out with a really whacky and very offensive point of view, I would check my facts a touch, but we'll give these guys some slack. They need some info. That's fine, we give them a book and send them home.

2) They are not relating to the holocaust as a historical fact, but as something else. OK, this gets a bit darker. Why would someone need to believe industrialised murder of jews (and others but mainly jews) didn't happen? Why would they need to communicate that belief. What agenda are they promoting, and should they be allowed public space to promote it? Is there a danger that their beleif may come to be seen to be legitimate? Maybe, even, a valid point of view?

I don't know about criminalisation, but there is a difference between being open minded and saying everything goes. If we are criminalsing not a private opinion but public advocacy, well, maybe its OK to impose some rules on public debate.

Ah, hell, I haven't even managed to convince myself. As you were, gentlemen.

Nice to see you around, Odin.