The way I heard the story, Alexander Nix was a chronic exaggerator who pushed the narrative that CA had a huge impact on Brexit and other elections when it simply wasn't true. He did this in order to gain more sales. They said the Facebook data was deleted by the time of the Trump campaign.
My theory is that they are not so different than a typical digital ad agency but they got caught up in a political tornado. I think we should at least be open minded to the possibility they have been scapegoated here.