“Behave ethically or we don't work with you" is Apple’s power”
I agree with this. Presumably it’s what Apple is going to do in this case.
What would you suggest they do if they can’t find a more ethical alternative to Wistron?
“Apple wants to be a world-spanning power.”
Does it? Or does it just want to keep making computers and software? It’s not obvious what Apple’s size has to do with Wistron breaking their contract.