Isnt Saturn the american counterpart of Opel? Not sure if they are part of the deal with the sale to Magna
And.. why?
It's because they don't want Ford to have any serious competitors Opel were Ford's biggest competitors in Europe and now that Ford have starting bringing the European models to the US Opel would have been the best placed to give them some competition.
That and America is the land of free competition and wouldn't ever dream of restricting trade
There's hardly any Opels in the US anyway.