People who deny or are ignorant of the Holocaust generally do not support Israel. History has shown that without an informed citizenry, it is almost impossible to reach a rational common consensus.
You’d be surprised how many Jews don’t support Israel.
It goes back to before WWII, where the Jews in Europe, especially in Poland, were divided between Zionists, who wanted to establish a Jewish homeland, and the members of the Jewish Socialist Bund, who abhorred the idea, because they felt having all Jews move to Israel would detract from their goal of a worldwide socialist revolution.