Truman's desegregation was certainly not a move made with electoral popularity in mind. I can't imagine many other politicians lighting that sort of firecraker in an election year.
He was certainly the first President to do anything significant for Civil Rights in a while, though you are correct Eisenhower shouldn't be dismissed for his positive legacy on the issue.
All the Presidents from FDR to LBJ made some progress on civil rights. But then Nixon had his southern strategy. And Reagan launched his Presidential campaign in Philadelphia, MS saying "I believe in states' rights". Pretty blatant dog whistle there.