And I would ask what choice they have today. They have an invasion forced upon them that will only end with violent overthrow.
I don’t see a single unified movement opposing immigration, I suspect there will be constant bickering, with some complaining one side doesn’t go far enough, others saying they go too far, etc. That’s the key, to unite the opposition.
You didn’t have to be a Nazi to think that the Versailles Treaty was wrong. But the Nazis were the ones who seized that issue and used it to achieve power.