This really isn't an argument I want to get involved in, since it is a fantastic waste of everyone's time, but I have to take issue with Aaron Timbrell's comment that "Most of the rights to RISC OS had already been exclusively licenced/sold to third parties before Pace became involved".
I worked with Acorn on deals involving technology licensing for a number of years, and one thing they were always very careful about was protecting their IPR. They never exclusively licensed anything to anyone. While I can't claim to know the details of any particular deals, I think that the idea that any of the rights to RISC OS had been exclusively sold to any third party is unlikely in the extreme, and hence Pace would have acquired the all the fundamental IPR - subsequently sold to Castle.
Anyway, the people involved are all perfectly capable of coming to an agreement if they want to. To mix a metaphor, they can either bury the hatchet, or use it to cut their noses off to spite their faces.