>> Linux vendor Red Hat, and 17 other vendors, have protested.......
Sounds more like sour grapes from those being left out to me.
I don't agree that business's should be dictated too with being told who or what they must do, just because the competition opposition does not like not getting the contract.
Besides which, possibly changing all of the operating systems and software would cost 10s of thousands of pounds, which is not in the best interests of their shareholders.