What are they incensed about? They defeated him.
Custer was an officer, but the hundreds of GIs that died in the battle were enlisted if that makes any difference, if it doesn’t (which it shouldn’t) then perhaps you should look into how the Indians treated the POWs of the American soldiers taken at the “battle” of little big horn, Civil War, Spanish American War, WWI, WWII, the GIs deaths can’t always be mocked can they? The American GIs that died during the many decades of the Indian Wars deserve our respect and for us to honor them.