Actually, Robert Byrd was a "Kleagle" and an "Exalted Cyclops" in the Klan, not "Grand Dragon," before he repented. He declared it "the greatest mistake I ever made." Although he filibustered against the 1964 Civil Rights Act, he apparently changed his mind and voted in favor of the 1968 Civil Rights Act.
I have been friends with a Klan member. I have been friends with, and related to, many white supremacists. I am the descendant of a whole line of white supremacists on my father's side. I strongly disagree with white supremacist viewpoints and consistently take a stand against racism and prejudice.
Jesus was a "friend of sinners" (Matthew 11:16-19; Luke 7:31-34) and was condemned for His associations.
I always find it curious when self-identifying Christians attack others on the basis of their good relationships with sinners.