North Carolina, where the new data center is, is EST just like NY.
NYC has big media companies and their CEOs, news media and their taping studios, and Wall Street.
North Carolina has a big building full of Apple's servers. (If it's even up and running yet.) You don't set the time for a press campaign based on a big building full of hardware.
From the point of view of an iTunes user, the NC data center is irrelevant. It's a hidden implementation detail. The iTunes store could be running on a G4 Mac Cube under Steve Jobs' desk, for all it matters.