In this passage, Graham is talking about the film Sayonara, in which Marlon Brando stars. The film looks at issues of racism, in this case racism with regard to Asians. Brando plays his character with a Southern accent.
Graham says that this is an example of Brando buying into a liberal Hollywood stereotype about the South. She says that he (the director is in on this as well) is stereotyping Southerners as a group of people who are typically racist and who are harmed by their own racism. They can only be redeemed when they rid themselves of their racial prejudices. By playing the character as a Southerner (which he was not in James Michener's book of the same name on which the film is based), Brando is doing what liberal Hollywood typically does. He is stereotyping Southerners in a very negative way.