I think Castle's point of view is that if you could run RISC OS on a PC, they can't sell any desktop hardware. It's the same reason as say, Apple, they don't let you run Mac OS X on any old PC, because their sales would suffer, it's that simple.
I think killermike is quite right, it's probably just as easy, if not easier just to rewrite the entire OS, or build it on top of an existing kernel. Of course this has not happened yet, although there is no technical or legal obstacles. It would take a group of very good programmers a long time, yes, but there are many examples of os-rewriting success.
I think what we used to have is two under-developed strains of RISC OS, now we have the potential to unite around one strain of the OS, which could potentially get a lot more development. Personally, I'm not bothered about the licensing of RISC OS. If ROOL will make RISC OS better, and make it available on other hardware devices, which in turn make it more attractive to new users, then it must be a good thing.
The fact is, get a typical geek (that's not an insult, I consider myself a geek), and show him an Iyonix, he's going to think 'cool, but £799, nah, too much', get the same geek and show him a Nokia 800, and tell him RISC OS is optional, he's might think 'That's quite cheap, I'll give RISC OS a go, if it does not work out, I'll just use it with the standard Linux OS'.