The Scalise-Duke story illustrates the position of racism in the current Republican Party. No, they are not all racists, but they must tolerate a little racism in order to keep racists in their voting coalition.
Compare it to how Democrats treat pacifists. I doubt whether many Democrats are pacifists. Obama's statement: "I'm not against all wars; I'm against dumb wars," probably holds the center of our opinion. On the other hand, most of us respect pacifists and accept them into our coalitions. And most pacifists are Democrats, at least when the time comes to vote: pacifists think that politicians who are against dumb wars are better than politicians who go looking for places to bomb.
(The first woman to serve in Congress was the only vote against entering WWI.
She lost the next election, and did not get back in Congress until 1940.
She was the only vote against declaring war after Pearl Harbor, and lost the election of 1942.)
Current "conservatives" want to repeal a good deal of history; which history to repeal is a matter of disagreement among them. They all have to get along, though, and the people who want to repeal the 17th amendment -- election of senators -- aren't ready to criticize the ones who regret the 13th. (Which means it is really reaction, not conservatism. Opponents of SS in the '30s and Medicare in the '60s were conservatives. Opponents of either today are reactionaries.)
Still, the Republican Party must carry the suburbs. And suburban whites are leery of too-blatant racism. So what you think doesn't bother the rest of the Party, but what you say may. It's all right to say that blacks should demonstrate against black-on-black crime rather than against police shootings; it's not all right to say that blacks were better off on the plantation.