They asked what could Apple do your YOU. In this case the "you" is the worker. They are saying the worker has no incentive to reveal to Apple that they are their agains their will. Apple filing a breach of contract does not help you in any any. Apple will leave and you will just be a slave on some other assembly line in the same factory.Apple faces a similar issue with underage workers in China. They're typically one it two years too young and they want the job so they provide fake ID and use bribes.
Apple's inspectors are still able to catch it. Ask for proof and verify the proof hasn't been forged.
It would be a breach of contract - which means Apple can cut ties with the company and not pay for whatever they manufactured - while also not allowing them to sell the goods to anyone else either (because it's all proprietary).
For nearly all components Apple has more than one supplier - which means they can drop them without any serious disruptions.
Given Tim Cook's track record on issues like this, I'm going to assume he's telling the truth. It's either very well hidden or they're not doing this at Apple factories where they know they will be subjected to close scrutiny.