I think you are defining orthodoxy differently than how the question is using it. It seems like you are thinking of religious orthodoxy (like orthodox Judaism) and equating orthodoxy with religion and therefore obsequious/sycophantic because they are similar to being devoted to religion but that’s not what the question is saying here. They are using orthodoxy to mean “authorized or generally accepted theory, doctrine, or practice” which corresponds with conventional and prosaic since they both mean traditional or accepted. Does that make sense?