They just had to include that last bit, didn't they? Setting aside the fact that "the subjugation of indigenous people" in the American west began long before the transcontinental railroad, and so the whole comment is debatable at best (the Trail of Tears was 1831, and the first Apache wars were in 1849; the Oregon trail was 1830-1840, and the transcontinental railroad was begun in 1863), it's the sort of drop-in to an otherwise unrelated story that makes you cringe.
Literally anything in the world can be tied back to oppression of a people, if you want it hard enough. You're writing a nice little human-interest story about a train ride...can't you give it a rest for a minute?