Supporting Confederacy or Nazis is un-American
During the American Civil War, over 360,000 Americans died fighting the traitor Robert E. Lee and the Confederate States of America to rid the country of the scourge of chattel slavery.
During the 1940s, America turned its military and industrial might totally toward ridding the world of the Nazis and their racist ideology. Over 180,000 Americans died fighting the Nazis during that war.
Basic logic tells you that any sympathy or support for either of these racist ideologies is un-American.