I agree and would think this was a way to hide behind a general premise to make the whole thing work, and yes the trailer is misleading to a degree.
Would assume making a movie about an actual Civil war in the US would not be a wise move even if fictionalized.... everything is way too politically charged these days.
This way they can kind of hide behind the journalism story but still comment on the political divide without taking sides basically.
Its a bitch move but I get it...

I am sure no studio on the planet would take on an actual US modern civil war movie, that would take huge balls.