China's situation does have something to do with it (you can't buy paid apps on Google Play here, YouTube is blocked and Google search frequently has 'technical problems'), and that's probably Samsung's excuse, but other manufacturers manage to keep Google services on their phones (although often alongside their own or another 3rd-party app store). I think it's just Samsung taking advantage of the situation to avoid paying Google's fees, not a case of gapps being legally banned in China.