not because they don’t want to, or wouldn’t if given the chance. If they get nukes that would change.

You have zero evidence of this, just rascism and vibes. This is basically what a Russian supporter would say about Ukraine. This is what the US did say about Iraq. This is what every imperialist prick says to justify their aggression.

And even if it was true, the actual, real life, actually happening genocide that Israel is committing is worse than the one you imagine Iran might.

were both bad and the obvious lesser evil

I'm going to stop you right there. If you think it's "obvious" that the western allies were lesser evils but can't tell that Iran is, you are a white supremacist. It's that simple. Remember, unlike Iran, the British Empire committed actual genocide.

the Soviet union less so.

Only if you're a Holocaust denier.

They had their own genocide(s) they just weren’t able to scale it up fast enough before getting invaded.

And this is just straight up false.