ROL had an exclusive licence to use RISC OS in the desktop market and they paid a lot of money for it. So not even Pace had the right to use it in that market without asking ROL. Castle could sell the stock of RISC OS ROMs in their RiscPCs and A7000s, because they had been produced by Acorn before ROL's licence was issued. So where did you get the idea that there was anything legal about Castle using a version of RISC OS in their IyonixPC desktop computer without a sub-licence from ROL? So Realist seems to be right in a way. Castle abused ROL's rights wich resulted in lost licence fees, and thus in financial damages to ROL. Because of that Castle was also able to offer their new desktop computer at a lower price, thus gaining an unfair advantage over their competition, likely resulting in lost sales for these companies.
Also we all now that ROL did quite a lot more to their version of the OS than only "CYMK sprites, round buttons and gradient backdrops". Also very few of us know what improvements they have done to RISC OS over the last year, maybe they have finished their ADFS replacement, wich might well support UDMA. PCI support is present in the Omega and probably also in the A9. The A9 probably also has USB 2.0 support, as well. Gigabit (not Gigabyte!) network support is a hardware issue, it probably would not be much harder to produce a gigabit network card driver for RO 4.4x than for RO5.xx. The HAL is only a minor issue, both versions of the OS have a good level of hardware abstraction.