Where are you getting the fact that the iPad uses AdobeRGB?
iPads have, until recently, been very narrow gamut devices.
From the introduction of the iPad 3, the screen's color coverage is close to but not quite the entire sRGB gamut. Rec 709 uses the same color primaries and white point as sRGB but has a more tuned gamma curve for darker viewing environments; these differences make Rec 709 and sRGB pretty interchangeable when it comes to non-color-critical viewing.
I'm not sure what the iPad 4 is rocking but chances are it's similar to the previous generations to keep screen costs low.