about the game theory,
there is not only money.
there is timing too.
Rossi have nearly no money, all gone to attorneys, and cannot expect long time to enjoy his assets, as he is old.
He have no reputation, and maybe his only asset is keeping plausible debiability of fraud charges to the most gullible victims, so he can enjoy adulation and why not fresh money.
Darden have a long careeer, and big money at stake.
In a way as Jed said it is heavily asymmetric.
Rossi case is desperate, which is a force, and he can take suicidal risk, as he is already dead from rational point of view.
It is clear from the docket that either he is full fraudster, or simply a crazy inventor who screw his partners one after the others. You conclude that , not from opinion, but from his own evidence.
The problem is than jury can be unpredictable, and it can even predicted taht facing conspiracy theories they cut the baby, making Rossi have to pay what he can (nothing), and darden pay part of it (much). the current hate against big money make this falsely balanced issue quite probable.
IH, and Darden , have much to lose, not only dozens of millions until IH is banckrupt, but damage on reputation, for IH, for Darden, and for... LENR (maybe the most damaging if Darden believe like me in LENR).
The most damagin would be to give some credibility to Rossi, and about that point is is a damage control, not a victory or a defeat.
IH have nothing to win in a victory, and Rossi will refuse to pay, delaying until he expires.
I wanted the fraudster to be hanged, but justice today is crazy and they could have hanged everybody thinking it is fair.