There's the old and not as often used "stereotype". But it doesn't have the emotional impact like racist does, so... Anything that doesn't hit squarely at the pathos is right out.
Otherwise known as appeal to emotions. I think I'm going to start finding examples of avowed racists who criticize lynching so I can do the 'not all racists' thing.
Why does it have to be insulting? Rather, why do you have to import shame from an unrelated activity to make your point? It seems to me like that trivializes racism and doesn't do very much to bolster this argument.