I finally watched that today. Hilarious. Jim Rome had a good segment about that. He basically boiled it down to the dilema a staffer would have in prepping Oprah for the segment.
If you were to tell her, "hey, he has a birth mark on his face so don't try to wipe it off with your fingers ok?" she's going to think you're an idiot for even suggesting it. Or if you do nothing and she ends up doing that, she's going to try to blame someone for not telling her about it beforehand. Funny