Their discovery in Autozone is about the possibility of Autozone having files compiled on SCO's UNIX on their Linux systems. Such files are compiled statically linked, and would therefore include SCO's copyrighted libraries. This could be a problem if Autozone didn't have a license to do that (which they claim they do). It has nothing to do with SCO code in Linux.
As for IBM, SCO has been backpedalling big-time on their copyright violations claims since the evidence never appeared.