They are two separate individuals. Bill Cosby is an entertainer. Whenever he goes into that mode, he wears a mask of what he wanted the audience to believe he was. IE: he wanted people to think he was his character from the Cosby show. He wasn't Cliff Huxtable in his private life.
Everyone wears that mask. What you do and say at home compare to outside when you interact with the general population is a separate person. All entertainers (music, sports, movies, or etc) do that. How you perceive your local news anchor compared to how that individual acts off the air is completely different.