I agree with this. Locking him up makes him a martyr to his supporters. By silencing him, it allows his supporters to claim that the authorities are hiding the truth.
The best way to deal with people like that is to let them speak, and to disprove his claims.
There are valid points to not locking them up for these sorts of issues, but disproving the claims they make cannot really be done as their claims are unfalsifiable as any conspiracy theory claim usually is.
Reason why I, in one sense, I'm with disciplining conspiracy theorists is that they often always spout these nonsense for their own selfish egotistical purposes (being inconsiderate of real victims and people who are actually innocent) and not because they have a real sense of justice for the sake of the country or the world.
I don't know a huge ammount about the holocaust. TBH I've always found documentaries on the subject a bit stomache churning.
I would have assumed that the rough number of people killed by the Nazis could have been worked out.
If there is no way of proving the numbers of people killed, then is it possible that the official estimates are wrong?
Only possible in the sense that it is possible that you might not be the person you make yourself out to be even if you were to post pictures of yourself and post YouTube videos and such. Or even if I were to meet in real life the person claiming to be Butterflies here. If I don't want to believe you're Butterflies, I may never be convinced by any evidence that you are.
That's how it is with Holocaust denialists. You can point them to all the evidence you want, but you can't prove the Holocaust happened.
There's a difference between proof and evidence. Evidence (no matter how strong) doesn't necessarily always point you to the facts and truths.
We do have strong evidence either way. For criticism of Holocaust denial, check this Wiki link:
http://en.wikipedia.org/wiki/Criticism_of_Holocaust_denial