You are not understanding the reason why President Trump says what he does about China and President Xi. He is making it possible for Xi to re-design his strategy towards the U S. in a better way, at some point without losing face. If Trump were to be verbally mocking or shaming towards Xi Xi could not adjust his decisions more constructively without looking like he is kow-towing towards someone who spoke ill of him. Xi must save face, it is critical. In some cultures it is absolutely everything.