While this bigoted unauthorized supplement is pretty reprehensible, we must always remember that the left has a long history of creating and manufacturing hoaxes, whether of alleged sexual orientation prejudice, racial prejudice, gender prejudice, to further their own interests. So, pending proof that this came from actual KKKers, instead of from leftwing propagandists, I will withhold further judgment as to the source.
I'm with you. Liberals are liars. Ask Rush - about the fake "I've been a Republican for 20 years... BUT" type callers. Or the same ones who call CSPAN on the "moderate" line and often on the conservative line with "conservative hatred".
I had a liberal friend who wrote fake "letters to the editor" stuff pretending to be a whacked out conservative. And he was doing it for a presidential campaign (not this one - it was some years back). So I don't put anything beyond them.