This was obviously what SCOXQ.BK wanted to begin with, a nice payout to STFU and go away.
Problem is, given IBMs deep pockets, it would encourage all the other trolls to come out of the woodwork looking for a similar deal. IBM is making them the latest Horrible Warning about frivolous lawsuits against them.
The other issue, that I honestly think the SCOundrels didn't take into account, was that charging IBM with stealing code, when their consulting arm works with any number of Fortune 100 companies, was a charge they couldn't let stand. Buying them off gives that charge credibility, where reducing them to a greasestain on the Utah sands proves the baseless nature of the case (the millions-for-defense-not-one-cent-in-tribute argument).
SCO's lawyers took a flat fee for handling the case through all appeals; at this point they're running up time they can't bill for. IBM can post a couple of interns on the case and wait until what little cash SCOX has left is burned out, then graciously propose a settlement involving the public flogging of all current and former SCOX execs and a full-page ad in the SLC Tribune calling SCOX out as a malicious copyright troll.
[ Disclaimer: 12 years at ATT; seeing these vermin trying to troll based on the legacy UNIX source code has pissed me off to no end, and wrapping them in bacon and trolling them through a school of great whites would be less than they deserve. ]