African Americans dislike for Jews and Israel is a throw back to the 1960’s and the Cold War, when Marxists made Jews out to be the blacks’ enemies. Walker grew up in that era, and that is the source for her disdain.
A lot of American Jews were active in the civil rights movement. When the three civil rights workers were killed in Mississippi, the two white men were Jews from New York. It's the old maxim of "no good deed goes unpunished." There is already a strong whiff of anti-Semitism in
The Autobiography of Malcolm X (Malcolm X, of course, was scornful of the civil rights movement because it sought integration with white society, not rejection of all whites).
Sharpton et al. seem to have fastened on the Trayvon Martin case in part because they mistakenly thought that Zimmerman was Jewish.