The thing I like is the reference to Aristotle. Today, there are some people who are too quick to brand anyone who disagrees with their enlightened views as a "moron" or worse. There's no winning hearts and minds that way. It's better to gently point out the mistakes of those who are otherwise worthy of respect, in the hopes that this will spur others towards self-reflection, than to castigate and put people on the d…
If we had everyone in the country run a race and the fastest were forced to move to the west coast and the slowest forced to move to the east coast and we waited a generation, people would start saying west coast people are fast in general. And they wouldn't be incorrect. So I don't see anything wrong with Aristotle saying the group of people who end up slaves are inferior, they provably are because they've been tested and selected for failure.
Saying Greeks are superior to Iranians or some other general pronouncement about ethnicity and attributes may not be correct, the DNA of the human race is mostly the same between ethnicities anyway, but saying Greeks are superior to the group of people they defeated in battle and enslaved in person is a tautology.