You can fight without unions. Tell the truth about LLMs: They are crutches for power users that do not really work but are used as excuses for firing people.
You can refuse to work with anyone writing vapid pro-LLM blog posts. You can blacklist them in hiring.
This addresses the union part. It is true that software engineers tend to be conflict averse and not very socially aware, so many of them follow the current industry opinion like lemmings.
If you want to know how to fight these fights, look at the permanent government bureaucracies. They prevail in the face of "new" ideas every 4 years.