This all hinges around the GPL - it's the first real test of it.
Caldera (who owned SCO and have since changed their name to SCO) released various flavours of Linux (I still have some of them on CD) under the GPL. At that point they released all the code in their distributions under the GPL.
If the issues with the code do exist, then at that point they gave away the family jewels.
The issue for SCO is to prove that they (as Caldera) did not knowingly release the alleged SCO code under the GPL. Everything else is IMO a dead issue as long as the GPL holds water in court!