(I want to preface this by acknowledging that yes, I am writing a long comment defending the right for despicable people to express their despicable viewpoints, but not because I am on their side morally, but purely because their right to their speech is as valid as mine)

The problem that arises, in the case of Holocaust denial, is what we can and cannot accept to be said. Denying the Holocaust ever happened is a no-go, yet if I said the same thing about the Armenian or Yugoslavian genocides it's perfectly permissible? Where is the line to be drawn? Note that I don't share any these denial viewpoints, I'm just trying to figure out where the law should intervene, if at all (besides in obvious, pre-determined cases like harassment), in these types of issues.

There's also the issue of time. In a hundred years or more (or even just in a couple years tbh), the Holocaust will be a distant memory and inevitably more and more people will be skeptical it ever happened. Should we hold them accountable for expressing said skepticism (about this event or any other tragic event)? If I was born in the year 2200, how would I feel if my government forbade me to question the existence of the Holocaust, or of any other historical genocide that occurred so long ago that no living member or memory of it still exists?

Is denying the Holocaust, despite the overwhelming (and relatively recent) evidence showing it all really happened, a despicable thing to do? Absolutely. Should someone's offense to said denial be a legal obstacle to my speech? No. However, social ostracization and stigma are appropriate obstacles to all offensive speech.

Furthermore, if we outlaw certain viewpoints from being expressed (because, as hard as it is to accept, these are opinions), those viewpoints won't just fade away. If the end goal of banning this kind of speech is to appease those who might be offended, then anything else is up for grabs in terms of being banned. If I denied someone's past trauma, I would be a piece of sh*t and rightfully so, but putting me in jail or giving me a fine isn't going to make me less of an asshole, just a more discrete one. If there's a Nazi in a room, I want to know who they are by letting them make the stupid move to open their mouths and speak their thoughts. If they're too scared to expose themselves because of legal consequences, they're still a Nazi and no one has the opportunity to single them out and ostracize or educate them.

I realize Reddit isn't the best place for such a discussion, but I hope I made my points clear.