1977 Star Wars doesn't have particularly clear politics, it's a fairy tale in space. Yes there's an allusion to the old republic but the entire story revolves around rescuing a princess which implies some kind of monarchy. Neither of these aspects is developed in the film. The politics of the rebel alliance are not expounded upon (we don't even learn who is allied to whom). It's just not that deep on its own and the assessment is correct.
They literally genocide an entire planet onscreen and nobody even bats an eye. The death of Obiwan has more emotional impact in the narrative !!!