I don't think that there's any suggestion that MD "haven't bothered" to provide Simtec with what they need. If you read the MD statement, it implies that they are at the 'testing' stage. Moreover, my guess would be that there's more involved than simply handing across 'software' to Simtec, and that part of the process has involved documenting the Omega's 'low level' software.
Surely it's a good thing that MicroDigital have listened to customers -- present and potential -- who said that they wanted networking first? The MD update also notes that "some of the above activities are being progressed in parallel", so USB may not have to wait for ARMTwister's appearance.
"At this rate, they might be finished by about 2015."
By which time, Select may have appeared on the Iyonix
Good to know that RISC OS will still be around that long. See you at ROUGOL in 2015?!