Per the article, CU2S was well-characterised in the 50s. The CU2S was a confounding factor because 104C is where it undergoes phase changes, which drastically

Per the article, CU2S was well-characterised in the 50s. The CU2S was a confounding factor because 104C is where it undergoes phase changes, which drastically change its resistivity. So the change in resistivity was from the CU2S impurities, not the LK99 itself. As the tail end of the article notes, when researchers grew a completely pure crystal of LK99 they got a strong insulator (in the mega-ohms). And as a nearby commenter notes, neither 0.02 ohm-cm nor 0.002 ohm-cm is even a good conductor: typical conductor metals (gold, copper, silver, aluminum) are under 3e-6.