Language has powerful connotations. When western journalists use the words "genocide" and "concentration camps" to what is happening in Xinjiang, most Americans think, consciously or subconsciously, of what Hitler did to the Jews. From there, it is easy to make the mental jump to associating Xi Jinping with Hitler. This association then makes it very difficult to deal with China.
I don't have the details about what is happening to the Uyghurs in Xinjiang, but I question whether it is responsible to play this kind of word association game when so much is at stake, because if Xi is indeed Hitler, then what is there to negotiate? If he is not Hitler, shouldn't we be more careful in the words we choose?