You don't have to be a liberald to note that he was, at one point, very racist. He ran on the platform of 'Preservation of segregation'. If that's not racist, I'm not fat.
That aside, he didn't stay racist, and that's more important than what he did when he was young. The measure of a man is his abillity and willingness to change his mind when he realizes he is wrong, and S. Thurmond changed his mind. That's more important to me than any crap he spewed back in the 40s.