I mean, c'mon... Were the notebooks acquired before the leak? If so, is Apple making these things -- or someone retrofitting shrink-wrapped goods -- on the off chance that it will land in the hands of someone that has information valuable enough to make it worth such a shotgun approach? Also, while you can fit a small computer in a tiny IC, the sheer amount of data processed by a modern laptop or desktop would make it an unenviable task to determine what is valuable information, and what is not.
From the Snowden documents it has become clear that they do intercept packages and bug the equipment therein. It is easy for them to get hold of shipments to a targeted person, manipulate the contents, and have it continue to ship to the destination. It's not unthinkable that certain reporters/newspapers became a target, given the previous leaks.
OK, not that I have any experience in espionage to back up my stupid opinions, but it seems to me that this kind of thing would have to be a targeted attack to be feasible. Much easier to go old-skool spy and plant a bug in the office ferns than to unleash an army of voyeuristic MacBooks in the vague hope that one will fall into the hands of a newspaper that will receive copies of confidential documents that the backlight inverter will then modulate in such a way that the NSA can pick it up with a pair of bunny ears. Ditto with the i2c controller or 2KB of flash in a trackpad.
As mentiooned, it easy for them to intercept specific parcels. Have you seen the video that i linked to? They are quite sophisticated when it comes to implants. Also, the BIOS of a computer makes a really good target to plant bugs. And, if for a moment we assume that they did intercept the delivery of a machine, what makes you think that the flash still has only 2KB? Let it have a few MB and that is enough storage to sniff keyboard input during the times the machine has no network connection, only to be sent out once it is connected again.
Really, take a look at what is already published from these documents. It's not hard to find. You can also download a PDF for free that contains a selection of these documents, on Glen Greenwald's site about the new book he just released:
http://glenngreenwald.net/What they do goes way beyond "just" sniffing on someone, with bunny-ears. And keep in mind that so far only a tiny fraction of documents have been written about or released. But that is already enough to make it clear that such a scenario is far from fantasy, or hard to accomplish for them. Combine that with the sheer dimension of their senseless spying and intercepting, and you get the idea. Heck, they even actively manipulate equipment that is at the core of the network infrastructure.
Greetings,
Chris