Whatever happened to free speech?

I saw in the news that a conference was being held in Iran to discuss the Holocaust, and oh boy did it cause alot of uproar! People were so mad that people were questionning history and discussing that specific incident in history. I was so shocked! I mean I used to love history in school and part of the reason I did was the fact that history is so fascinating in how its all pure interpretation. I mean many people can explain the same event in totally different ways...motives differ, opinions differ, events are portrayed differently. So essentially history is ALWAYS up for discussion and can always be challenged. That's what makes history history! So why not have people discuss the holocaust? What's wrong with that? How can people say "don't discuss this because you have no right to"?! Its ridiculous! So everyone was fighting for free speech when the Danish cartoons were published but now with the holocaust everyone is being asked to shut up? There were people at the conference being interviewed and they were told by their peers NOT to publish anything from the conference that had anything to do with how many people were killed in the holocaust and with whether the holocaust actually happened or not...so people were actually told to keep their mouths shut! What happened to the free speech you were just fighting for?! It's history...its meant to be interpreted, discussed, and challenged!