Nanni wasn't the only one, just the most famous.

Like, we found Ea Nasir's house, and it was filled with evidence that at one time he was trustworthy, and then just went to shit.

Like, we know ~5 other customers of his by name because they also left written records about him not delivering or cheating in other ways.

It wasn't a one off thing.

Upon reading his Wikipedia page, it seems that we likely didn't really get him wrong. Not too wrong, anyway.

They found multiple complaints from different people, at some point we have to accept his copper was bad

I read a history blogpost claiming that Ea-Nasir was a patriotic (but hot-tempered) man who carried on trying to sell his home town's copper long after they had mined out the good deposits.