Perhaps, you know, because there are recorded instances of Palestinians actively helping Hitler.
Personally, I don’t see a connection between the Palestinians helping Hitler and the disrespectful comparison. Modern Israel shouldn’t be compared to the Holocaust because the actions in Israel are being done for the survival of a culture with claims approved by the UN (other than a couple circumstances) while the actions in Nazi Germany were done for the extermination of numerous cultures. Not to mention the endless difference in degree of inhumanity. 12 million people were murdered, and comparing their suffering to a much smaller scale conflict is more than slightly insensitive.
Note the use of the word conflict. The Holocaust was not a conflict. The only resemblance I can remotely see in this situation are the Palestinians and the Jews in the Warsaw Ghetto Uprising, and this is only due to the exchange in firing and resistance. During the Warsaw Ghetto Uprising, (please further research this event if you are curious) the starving Jews of the Warsaw Ghetto rebelled and held off the Nazi army for two weeks. To give a comparison that is accurate, the Nazis conquered France in one week.
However, the Holocaust was not a conflict. Israelis and Palestinians are killed frequently alike in this conflict unlike the completely different circumstance of the Holocaust which involved death camps. There are no death camps in Gaza.