I would have to take issue with a couple points here. For one, is it really vigilantism? Think of this law that was in effect in South Carolina from 1740-1865 called the Negro Act: It authorized white enslavers to whip and kill enslaved Africans for being "rebellious." This codification of white supremacy into law was done on the basis “that color is prima facie evidence”. That means if a white man, who the state gave power, could judge for him self based on skin color who was black and who was in need of whipping or killing for being deemed a “uppity” or rebellious negro. The legislative law was widely regard and mimic through the South.
This means until 1865, white men were deputized by the law, by the government of those states, to whip and/or kill a negro who that white individual deems or judges to be “rebellious.” Up until then, it was not vigilantism, since it was state sanctioned use of force by deputizing white men. I believe this is a justifiable basis at least for making the case that it is not mere entitlement that carries over after the Civil War, but an sensation or belief that the law is contained within these white men and that law that was cancelled by the US government was unfair in stripping white men of this deputized power. It was President Grant, a Union General who’s helped organize the defeat of the South and end that law, who campaigned on ending this “vigilante” justice, or as he said, wiping away and vestige of slavery and hence white superiority. He did so for the first couple years.
So the next point I’m picking at is just that you may be forgetting the 4.000 or so black American Republicans who Democrat Party (they were the MAGA party back then) slaughtered during the election of 1878, primarily in Louisiana. The senate report of 1880, a 1500 page document, contains evidence gathered from black Republican Americans who want to vote. The minority report by Republicans recognizes such “heroes of democracy” (my phrase, not a historical phrase) like Henry Adams, a freed black ex-enslaved, who taught himself to read and write, and walked through four states collecting evidence of these insurrectionist massacres to submit the USDOJ AG’s investigation that was focused on that particular 1878 insurrection. The 153 mostly black Republican Americans (liberals back then) who submitted evidence for this insurrection trial of 1859 probably would have been called on when the trail started, but Attorney General of the United States decided at the last minute to nullify or void the trial and no verdict was ever allowed to be reached into the violent overthrow of the black Republican (and some white Republicans organizing together) to peacefully note.
So you can see, although this was perhaps technically “vigilantism” I would say it was the spirit of legal state sanctioned empowerment from the previous one hundred and twenty years of law that was in the minds of those white killers. Of course, since their statewide slaughter fest was politically motivated by Democratic Party organizers (today MAGA wing) in order to win the elections, it also gives a political sanctioning, as the “White League” spearheaded the slaughters (sorry, no Klan, that was not in their state until the 1920s). The minority report also mentions the bloody one-sided insurrections to gain (or regain) political control in used in the run up to the 1872, 74, 76 elections.
One more small correction, that 1915 film you mention has a scene where the white men Klan ride into town to “redeem” after black and white Republican ‘fusion” party members won the elections of 1898 in Wilmington, NC, and through which the last black American Republican congressmen, from that ‘redemption’ of white power period, won the NC election that put him back in congress. The Klanners rode into town on horseback and shot up the town, killing elected black Americans and driving the rest of the white and blacks who won or organized out of town, and then installed themselves into power. This was the great moment of white triumph, since now all black American Republican power had been eliminated in the 15 state Jim Crow region. President Wilson, from the MAGA wing of the Democratic Party, has his famous quote in that film, of the “Klan being a veritable empire of the South.” So I would argue, as that then showed across the nation becoming the first Hollywood blockbuster, that everyone seeing it saw the President using his authority as Commander-in-Chief to praise the Klan’s achievement in making a “true empire” (over black Americans).
His quote acted as a triumphalist message that rang out coast to coast, giving presidential support of the continued and widespread lynchings and massacres of black Americans, the gruesome killing imaginable, where no white group of killers of black Americans were fairly tried until 1981. Hence my third point, the absence of justice is presence of approval, since everyone in the small town watched these lynchings, and were even invited by newspaper ads. You can’t make this stuff up, but you can leave it out all the history books in the 20th century.
Lastly, I would have to recommend your excellent critique which I enjoyed reading. It was detailed and you notice that absence is a type of presence when discussing the ‘our people’ motif in the song. It leaves me with more ideas and questions then answers, which is what those seeking insight do best. Thus, I am left to explore the most prominent question raised for me: Is it a ‘race riot’ when it is white men organizing with weapons and heading out with intent to harm by going into a black section of town? It sounds more like a white male human hunting expedition, though a better phrase could be thought up.
Thanks again and best of luck.