It's actually a front. The Maiden, NC facility is going to serve as a development center and proving ground for Apple's new Time Machine (not the backup utility, but a real one).
You've heard of a flux capacitor, yes? Turns out it's real. And when coupled with the right vehicle running at 85MPH, one can travel in time. Of course, it takes a bit of space to get the vehicle up to speed (especially considering today's fuel efficient vehicles), hence the need for such an expansive facility.
Additionally, the real reason Bertrand Serlet is leaving his post is because he has a special assignment to go back in time to knock off Eric Schmidt and Steve Ballmer. "Focus less on products and more on science" - that's your tip off right there.