A theory is put forward at Groklaw: Caldera apparently wasn't entirely above board with its IPO - the IPO seems to have been rated too positively by analysts and thereby manipulated. At least there was a corresponding suspicion that led to appropriate investigations.
Possibly IBM now also wants to capitalize on Caldera's IPO - and that could turn out badly for SCO (which were previously called Caldera) if IBM can actually draw real connections there. Stock market manipulation is not viewed favorably in the United States...
And ultimately, you can see from SCO's stock prices what the real objective of this whole affair is. The stock prices have risen nicely over the past few months, without SCO having a single current product to show for it.