Meanwhile: they clearly can't just revert the web page. Keys gave a hacker group a login for a web application. How, exactly, does Trib Corp know how much damage the hacker group did to the server? There needs to be an investigation, and the norm is that the investigation should be done by a third party.

Meanwhile, there's a principle in the law that you take the victim as they come. In US tort law, it's called "the eggshell skull rule". It means if you hit someone over the head with a book or something and unexpectedly fracture their skull because it turns out to have been as thin as an eggshell, you are still responsible for the damage you caused.