Uh... this is wildly untrue. You don't find XXX movies at mainstream theaters or Barely Legal magazine at Barnes and Noble. Likewise you'd be hard pressed to find your typical college-educated liberal at a christian bookstore.
You will find books, magazines, and movies with nudity and sex at Barnes and Noble -- far moreso than allowed under current App Store standards.
Also, to the point of the original app rejection, you will find plenty of material that mocks all sides of the political spectrum. A countdown to Obama's inauguration with a negative caricature of Bush is mild compared to what you can find in bookstores, cable-channels, and theaters.
Those outlets carry such material without their customers getting offended by their mere availability.
But after some point, with the image established, inclusion is the winning strategy -- or else money is left on the table, or an opening for other competitors emerges. Few adults hold a lower opinion of bookstores, cable-operators, and movie-theaters that include among their range of offerings some things that are diametrically opposed to their personal political/religious/social standards.
When does a a platform proprietor know when to shift? Is the shift best done rapidly or gradually? Even if the model is correct, is Apple being too conservative in opening up?