Ezekiel Starkweather:
I do think people are responsible for their own actions though. I do not think that one sociopath leading an army of men makes all those men sociopaths.
Custer is a Classic authoritarian. His men are followers, and I really doubt even single one of them enjoyed butchering women and children. They did it because they did not see another way out, other than getting shot for desertion.
In our world, possibly, though that ignores the agency of post-conscription troops (they could leave! Not desert, just get demobbed in '66, bam, out of the army) and the social surroundings that led to a morality where killing certain groups of people was all right because they "weren't
really people, or God wouldn't let us". Things get particularly sticky when you realise that a lot of those guys in our world were black northward migrants who were "proving" to their white officers that
they were civilised people by being the ones shooting rather than the ones shot. Our history is, however, irrelevant.
In
this history, we know these guys are all the specific kind of sociopath known as
mercenaries. They kill groups of people for money. It's their favoured career.
The guys
here? They chose this "kill the indians" assignment. They are absoloutely here to kill natives. Custer isn't herding scared sheep or leading them by force of personality: he's warlording. "You come fight for me, you get their gold and women". Knock him off, the mercenaries might faction, but all that means is you'd get 2-3 bandit chiefs wreaking havok rather than one, and then the Union Army sweeps in because of Martyr Custer.
Jackie never claimed Custer had to stay alive for her timeline's sake - she's trying desperately to
change that. She wants Custer alive so that the abovementioned 5000 hungry, rapacious armed men stay in a manageable block rather than spreading a wave of destruction over the countryside, splitting and fatally weakening the Nations' policing forces.
She wants the Lakota not to die.
Surely if Zek wanted Custer
punished, he shouldn't give him the easy out of being dead...that's, like, what all extremists want. Death or glory - proves them "right" that it's their way or nothing/the only way they're stoppable is if they're dead. Being captured and forced to see the consequences of their actions, or even more punishing, being gently led to repentance and
seeing the horror they have wrought for what it is, now, that is punishment.
If you shot Hitler after his rise to power, one of his buddies would have stepped up. We don't know if he'd have been better or worse, but you'd still have the problem of a Nazi-tolerant and/or -supporting population in need of a way out of the poverty and degredation enforced by the Treaty of Versailles, and unless you solved
that properly, no amount of individual murder would stabilise the region.