The exception to this is currency: if you're fairly paid with stolen money, you get to keep the money, regardless of whether the rightful owner is able to proof that it was originally theirs and stolen.
The fact that somebody may take a replevin claim against me because the digitizer in my phone was removed from their stolen phone does not, imho, have any bearing on Apple's rights and responsibilities with regard to me as a customer.
Sigh. You're both making claims that could be different between jurisdictions. If you don't know that, then you should probably stop now.
Depends on here you live. In some places, buying stolen parts is illegal. In those places, they would probably have a defense, since it would not be “fair and square”.