This isn’t an entirely accurate picture. In Hanink’s first book, she demonstrates how the classical Athens that we think of today was largely an invention of Athens in the fourth century BCE.

To oversimplify a bit, although Athens lost its military hegemony at the end of the Peloponnesian War, Athens and Athenianness maintained a powerful cultural influence for centuries.

I think the lede, then, is clear from the first paragraph: classical Athens (synechdochically represented through Thucydides here) is a construct that can be used for diverse ends, and we need to pay careful to attention to who uses it and how.