I saw that. Sometimes things have a way of surviving those kinds of events though. It's also possible that just by getting the rights to the stuff, they can piece together portions that would otherwise be inaccessible. eg: someone held onto a source tarball somewhere but doesn't want to come forward because of potential legal retribution. People hold onto mementos even if by accident in the shuffle of life. Maybe someone has an old book in storage or something?

The article also mentions that they are unsure if they can legally reverse engineer it. Getting the rights to Irix would definitely solve that problem too.