Lots of laws were ignored or creatively re-interpreted, by plenty of people & entities, during the unprecedented pandemic health emergency of early 2020. Many emergency actions taken by elected leaders have been later found illegal by courts.
But if there was no malice or net harm from such technical violations – or indeed if the breaches effectively prevented greater harms – society and the courts will often find such "law-breaking" to be forgivable or even praise-worthy. For example, you are allowed to break trespassing laws to save a life, and in other situations of private or public necessity.
With regard to reading & education in early 2020, publicly-funded schools & libraries that were supposed to be operating were closed with little warning, for a potentially indefinite amount of time. Millions of purchased books that were supposed to be circulating sat idle in locked buildings. A crucial cultural & civilizational function was stopped dead in its tracks.
Against that, the Internet Archive rapidly deployed a novel technological workaround to re-enable some (but not all) of the pandemic-impaired booklending/reading activity. It did so in a way that had no more effect on the publishers' economic prospects than normal-times library operations, and was arguably within the 'fair use' & format-shifting rights well-established for book owners & libraries in the United States.
So I think IA expects to "win" the lawsuit because they did a good deed for the world's readers, as a temporary & reasonable adaptation to an extraordinary emergency situation, that caused negligible harms to the publisher plaintiffs.