I wasn’t having a problem, but I was just curious about the question of whether or not it was necessary to make all your shouldAutorotateToInterfaceOrientation:interfaceOrientation overrides jive when using a UISplitViewController.
Sure enough, as is mentioned here in this Stackoverflow thread:
All of your view controllers INSIDE the split view controller have to override [shouldAutorotateToInterfaceOrientation:interfaceOrientation]… To make it rotate to all orientations, return YES in all overrides.
Makes sense to me. Thanks to Krumelur.