What is going on here is that denying the holocaust denies the narrative of the Jewish state. The reason for Israel is that Jews are unsafe anywhere but in their own strong and secure homeland. If Jews are safe in the rest of the world, then there is no need for a Jewish state to protect them.
If it wasn't that big a deal, then the in the view of the Arabs there is no point to Zionism.
Conveniently forgetting that Zionism got its start in France in Russia when Hitler was still running around in short pants.
So for the Arabs, Zionism is just a colonial adventure of European jews to enforce european values on the mid east, and rob and displace the original inhabitants. (The original zionists purchased the land they occupied, and even now when Arabs are displaced they are compensated and permitted court hearings prior to any eminent domain proceedings. The Arabs under Israeli law are better protected than US citizens under the most recent US supreme court decisions on eminent domain.)
I think this is what causes such a huge desire to get ahold of the history of the 1940s and re write it. You control the historical narrative, you can control the future.