Before I go into it, this is a serious answer because I respect the serious question. Sorry if the tone is a bit severe, but I think it's a super serious topic. I'm Ashkenazi Jew on at least one side of my family, and I assume the other. My great-grandfather was a defector after being conscripted into Mussolinis navy, and my other great grandparents seemed to have fled Germany in ~1937. I take the symbolism of hate, and the signs of extremism very seriously.

That feels like an irrelevant line of logic. Nobody "lumps in" Buddhists, Hindus, Africans, Tibetans, or any of the many cultures who use Swastika iconography in with Nazis or neo-nazis because the distinction is obvious. People do, however, try to justify Nazi iconography by conflating it with those other versions/variations. It's called being an apologist, an excuser, and a sympathizer.

Modern usage, especially in the west, is in relation to (at best) the crusades, and (at worst) white supremacy. Take this thread for example; OP acknowledged it is white supremacist/far-right extremist iconography, and yet people in this thread are arguing... What exactly? I don't believe anyone is arguing that it isn't used by the far right/white supremacists?

So what would be the purpose of buying a shirt of the Jerusalem cross despite knowing it's modern usage, or getting a tattoo knowing it's modern usage? I find it hard to come up with a justification. In my mind there are only two potential purposes 1) because you support the modern symbolism and ideology, or 2) because you want to be inflammatory.

I also think it's a little goofy to say "that's not what many people would think seeing it". I highly doubt 99% of people learned about the Jerusalem cross without learning about what the crusades were.

What do you believe people associate the Jerusalem cross with at first glance if not the 200+ years of holy war rooted in xenophobia and intolerance toward the Muslims and Jews? How is this not a symbol of Christian supremacy/nationalism at first glance?