I wouldn't call it a dog whistle - just terrible taste.

The tune features very prominently in the absurdly whitewashed but entertaining Errol Flynn movie, They Died with Their Boots On (1941), about Custer and the 7th Cavalry.

In that version, Custer (Errol) promises the Sioux they can keep their lands, but is subverted by crooked politicians and railroad millionaires, who set him and his soldiers up for destruction at the Little Big Horn.

I am sure that the planners of the musical program at issue have *no* concept of actual history, regard the movie (beloved by millions) as a pretty accurate picture of Custer, and regard him as a Great American Tragic Hero.
(The evil pols and magnates of the movie are easy to miss as representative figures, if you're either ten years old or morally obtuse.)

On the other hand, the tune must be especially galling to the Lakota:   it was the 7th Cavalry that fortuitously discovered gold in the Black Hills, inspiring the gold rush that led directly to the abrogation of the 1868 Fort Laramie Treaty and the seizure of the territory by the United States.