The argument (particularly from Haredi non-Zionist Jews) goes along the lines of this:
If the Japanese ruling class decided, one day, to say “actually, we , the Japanese, are the real Jews AND we are compelled to conquer, enslave, and commit genocide on the people of China in the name of Judaism” does that create an affirmative obligation of a religious Jewish person in a religious Jewish community from a long line of religious Jewish parentage in, say, the Iranian Jewish community (which still exists) to affirmatively do something because these people, on the other side of the world with no connection to them whatsoever other than trying to steal their name are “doing it in their name?” Are they “fence sitters” if they say “I don’t know anything about China and the only thing I know about Japan is that it has nothing to do with me or Judaism despite how they hold themselves out to the rest of you?”
This is essentially how religious Jews historically treated Zionism (for nearly 2000 years): “Zionists (particularly Christians), identify these people as the only “real Jews” but I see them as, at best, heretics and more likely Christian converts who have nothing to do with actual Jews in general and me in particular.”
The western positionally you identify is important but I think you are needlessly singling out Jews. Can any citizen of a western country (let’s just say US/UK) dust off their hands and say “nothing to do with me”? When the Zionist project is, at base, western colonialism? Would a Jewish American be morally worse than an evangelical Christian for doing that?
I think what’s getting me hung up on this framing is the idea that someone else, by essentially coopting one’s identity, creates a moral obligation on the victim of that co-opting that is greater than the moral obligation of the rest of the population to stand up against injustice when it should essentially be no different.
In a practical sense, a non-Zionist western Jew, when confronted with the facts and news all around them, is going to ultimately take a more affirmative political position (pro or anti). Just as any westerner should. But that is looking at the issue through the lens of the 2020s where it has infiltrated most of organized Jewish institutions and the local and country governments where they live. Once their synagogues and community centers become centers of Zionism and Zionist worship, they either keep going (implicitly supporting) or stop, so they have to confront the question in their daily life and few can escape to “the way things were” when you could be Jewish and Zionism was one of those political ideologies that was out there, like liberal capitalism versus communism or nationalism versus pluralism, that you could be a part of but it wasn’t a necessary component of ones identity and you don’t have to have an opinion on it.
The 74-40 tomatoes being unpeeled and unsliced in the picture is very confusing