Seems like lip service slacktivism that does nothing but inject a bit of weird misplaced guilt. Railroads were a huge technological innovation. Handwringing about the skeletons in the national closet without really understanding how or why the railroad played a role seems distracting. The quote from the article says, in essence: ‘railroads and the Indian Wars happened at the same time, kinda, so… railroads bad, maybe?’

And op’s point stands. Tech is power; and almost any tech can be used and abused. But tossing this in seems lazy at best.

Did you read the article? The sentence OP objects to is the lead-in to a conductor on a trip telling him about how rail passengers were encouraged to help reduce the native population. It's a bit of context for an anecdote, in an article that is entirely compared of lightly contextualized anecdotes.

You could remove the sentence I quoted, keep the thing from the conductor about bison, and it wouldn't make a difference to the story [1]. It's a "lead in" only in the extremely literal sense that the one sentence comes before the other one.

[1] It might even work better, since it lets you draw your own conclusions about the anecdote. Not everything needs to be a lesson.

I agree that the story flows better without it but I'm saying it is not irrelevant like you claim. It is bad writing if nothing else.