How many people have you ever met, or even heard of directly, that claim the Holocaust never happened? I can honestly say I couldn't name a single one, not even in places like the USA where they'd be able to make such speech under the First Amendment (not on Facebook). I've only ever heard about such people indirectly, via what censors claim about them.
Now how many people do you see who throw around the term "Nazi" like it's a schoolyard insult? That happens every day. I see people being compared to Nazis all the time, right here on HN which claims to have strong moderation.
The likelihood of this sort of censorship being applied to people who literally deny the Holocaust is tiny. Facebook have spent 2020 routinely censoring scientists who don't agree with the WHO, even though the WHO changes its mind every five minutes. Many of the people in high places in these companies seem to believe any disagreement with authority is worthy of censorship. They are not free speech absolutists who make an exception for truly dire cases.
So when are we banning everyone who says only 6 million people died in the holocaust?