Can you explain how that's relevant?
It seems like you're fixated on the use or lack of use of AI, as opposed to the fact that a lawyer trusted a 3rd party service that is known for lacking accuracy and then presented citations that do not exist.
Ask yourself... what would this look like if AI wasn't involved. Would a lawyer be liable if they just made up a citation...? What about several? What about in an environment where a number of them had done it recently, and therefore there was a standing warning against doing it again?