When the shoe's on the other foot you never hear the end of it.
Remember Obama's "black power" pastor, Jeremiah Wright; or Bill Ayers, his "commie, terrorist" friend?
We haven't heard the end of it. Bill Ayers and Jeremiah Wright get mentioned on some right wing blog or forum post about twice an hour. What Wright and Ayers actually said is a matter of public record and rarely matches what is attributed to them.
In the case at hand, we have a conservative Congressman who accepted a speaking engagement to an organization founded by a former Ku Klux Klan Grand Wizard. In the state of Louisiana, there is no confusion about who David Duke is, or what he is.
Representative Scalise accepted this engagement with full knowledge of his audience's political leanings. For him to say he only wanted to forward conservative economic principles is disingenuous to the point of ludacrisy.