Earlier quoted context omitted.
So guilty until proven innocent, then? This is exactly why the title calls Apple's practice an "exploit". Apple recognizes that CBP does not follow due process and they take advantage of that by slapping their label on every last little, insignificant component - including stuff the customer will never even see. It probably helps catch counterfeits, but it has the added benefit of significantly disrupting legitimate…
What does this have to do with providing a source? You are the one who wrote the, not trivially obvious, claim.
In reality, nobody knows why Apple is doing it except the people who made the decisions nor would it really be possible to trace the parts, but it’s far more likely that it comes from the many devices that can be salvaged for parts than it coming from some black market operation coming from the factory.