basically
Exactly.
Look at the quote from Wikileaks above. How can mailed packages containing iPhones look brand new and un-tampered with, if the packaging for the phone itself has been opened to infect the device?
There is only one foolproof way to get the phone looking like new again: send it back to the Apple factory assembly line to replace all the transparent plastic packaging needed to infect the phone. Wouldn't that take a while? Wouldn't the time spent waiting seem a bit strange to the customer
And isn't all this a little too elaborate? If you need corrupt factory workers working for the CIA at Apple assembly lines (which are gonna be mostly in China, of course), why bother with all the messing around? Why not just infect each and every phone as it comes off the production line, it's far cheaper and easier (and then, only the more senior staff need to be corrupt CIA workers, not regular factory floor workers)
How come Wikileaks can't figure this out for themselves, surely they're not so badly informed that they really believe any of this "intercepting mail" nonsense