Wasn't the Roman empire better than most contemporary polities? Like it created a long era of peace in a significant area and successfully integrated various population, culminating in the 3rd century where all free men were made roman citizens. If you'd ask under which ancient polity I would prefer to live, chance are I'll choose the Roman empire.

If aliens invaded earth and after decades of subjugation they successfully "integrated" us savages, they would view it the same way. The forceful destruction of all our culture, languages, religions, history, sovereignty, it would all be justified in the end because their alien technology and culture is "superior". I don't believe it's justified no matter how relatively primitive we are, and if aliens did it that alone would demonstrate their own primitive culture quite clearly no matter how much they whitewash themselves in the intergalactic history books.