Virg do not provide the flight deck for this operation, Atlanta do - so what is the problem with non EU nationals who have paid for the relevant conversions to their hard-earned licenses.
Perhaps if there were the resources available in the UK, Virg and other UK organisations would not have to go further afield to pull in extra capacity when required. Put up/shut up or go lease one yourself - pay for a UK/JAA AOC train the crews and then sit their waiting for the phone to ring! Please also note that Atlanta (apart from Corsair) are the only wide body high density charter aircraft operators in Europe. So where would you be doing your shopping??