***and since when is it bad to celebrate an American who stood up to a lying and cheating federal government who sends troops after women and children?***
Perhaps it is because the Sioux were invaders of CROW Indian territory, where the Little bighorn is located.
The CROWS were enemies of the Sioux and were scouting with Custer at that time.
Most 'invasions' were the product of displacement--like that from the Black Hills which would "belong to the Sioux until the sun no longer rises in the East", (which we now know to be gubmint speak for a period of much less than ten years).