Sidney Poitier: Why is he Oprah Winfrey's hero?

I am a fan of Oprah. She often repeats that Sidney Poitier is her hero. I never heard her say why he is her hero. What is so special about Sidney Poitier to have 4000 roses and limousine etc...to get him on her show? Serious answer please. The best answer will get 10 points. Thank you.