The same reason that the ONLY station he didn't appear on was Fox, back when he did that "peddling healthcare" tour on all the Sunday talk shows. Those stations agreed to ask questions from an Obama "approved list of questions", and Fox wouldn't agree to that.

obama wants a platform that HE CONTROLS by having a well crafted answer to a question he already knows is going to be asked.

He is scared of being asked a question that will reveal what an empty suit he is and will leave him stuttering, stumbling, and looking as stupid. He is scared his facade will be revealed and the sheep will see their Messiah for what he is: a complete and utter failure and fraud.

Or He could just be scared of "kwying & pissin himself" in front of the camera when big-bad-bill-oreilley challenges his bullsh*t.