The source code is proprietary. They’ll never release it. If Snowden has proof, then where is that?

Since both claims are unprovable, let’s look at the evidence and motive.

You believe that Apple would spend all of that money fighting the FBI in court, just so they could give the NSA a backdoor that is in direct violation of their privacy policy, potentially exposing them to a massive class action suit from users, and does not benefit them in any financially tangible way.

Time to take off the tin foil hat.