Just to continue the prior (as I didn't know how long it would be), there were no mentions of "Sacred Baby Mountain" in newspapers.com. Nor are there any when doing a general web search apart from those tied to websites reporting this specific story. Searching for "Captain Joshua LeFlore" draws a blank in newspapers.com; omitting his supposed rank brings up mostly wedding announcements, obituaries, a sale of land, and a murder case in Atoka, Oklahoma where a Joshua LeFlore pled guilty to manslaughter in 1899.
The so-called professor is an author who has a bunch of sensationalist books listed on Amazon, etc., but most of them appear to be out of print.
I will say that the Choctaw Lighthorsemen sound like an interesting bunch, breaking up political impasses (by forcing one side out of the assembly hall) in 1897 and enforcing bans on alcohol in their territory (after a sort) in 1902. One of their early leaders was indicted for introducing liquor into the Indian Territory (that's a legal term that is still used in court cases today) in 1914 and arresting some businessmen who circumvented the law to get a railroad run through the reservation in 1920.