It's not claiming that Israel represents Judaism, it is merely describing the group of people carrying out the genocide. Israel does not represent all Jewish people, however Jewish people from Israel are committing genocide.
Jewishness does not tie into why Israel is committing genocide. Also, the IDF is secular. If it was anyone else committing war crimes, why would you bring up their religion? Israel claiming that they represent Judaism is a trap, and it's important not to fall for that trap by associating Israel with Judaism. Judaism is not related to their genocide.
Why? Calling someone a Christian White Supremacist isn't implying that they somehow represent Christianity. It implies that they use their Christianity as a basis for their actions as a white supremacist. It is entirely accurate and appropriate in this context.
Associating Israel's war crimes with Zionism is not antisemitic, but associating them with Judaism is. If the 3rd panel said Zionist instead of Jewish, it would be just fine. Since the !memes@hexbear.net post seems to have gotten removed, presumably due to that, you might have more luck re-submitting with that change.