If the beauty of the classic Western at least partially lies in its dependably simplistic morality  —  a villain doing wrong; and a hero stopping them cold  — the modern “neo-western” as Ari Aster’s satirically topical film has often been classified, becomes almost the literal opposite: A film where morality shifts and scuttles about, before getting bludgeoned, shot, blown up, and, eventually paved over and turned into a high-tech office building.