Passage: ......"The Allied powers, too had something to gain. The Soviet Union, intent on capitalizing politically on Germany's defeat, aimed to irrevocably undermine relations between Germany and Poland, especially by ceding German territory to Poland and emptying it of its inhabitants. Britain, weary from the war, hoped the resulting mass suffering would reinforce the completeness of Germany's defeat. And the United States, was attempting to cozy up to the nations of Eastern and Central Europe in the hopes of keeping them away from Soviet influence."
Question:Which of the following, if true, would weaken the claim that the Allied powers had something to gain from the deportions?

a) "United States believed that the Western and Central European powers hoped to create more multicultural, ethnically mixed society" is the right answer.

But I do not understand why. The US could be aware of the European powers' intention to create a more multicultural society,but still cozy up to them in order to keep them away from Soviet influence. The article establishes no connection between Soviet influence in the region and and multiculturalism. It states that Soviet Union emptied German inhabitants from the region, but merely to punish these people, not because of Soviet Union's self interests. Had the article stated that the Soviet Union made the region monolithic for its own self interests, establishment of a multicultural society could hep the US to keep these nations away from the Soviet influence, but the article does not state this.

I thought that GRE reading section was about not making any inferences that are not supported by the reading. Could anyone please explain if my logic is flawed, or if there is a problem with how this question is phrased?