To act would have undermined his whole foreign policy meme since killing OBL - that Al Qaeda had been neutralized and the ME was all peace and light.
There's a passage in Mila 18 (Warsaw Ghetto uprising) in which a German commander in Warsaw is trying to explain to his superior why, given the German view of Jews, he is having so much trouble suppressing the uprising.
The Won finds himself in a similar situation, trying to avoid admitting that the "Arab Spring", whether by accident or design, has gone horribly wrong with respect to Western interests.
(Those of us with 1% of a clue knew from the beginning that it was "by design")