I imagine there's probably some community of government elites who are privately laughing about Trump.
This is hilarious. Basically Xi sees this guy and immediately pegs him as an idiot. He then proceeds to feed him the same propaganda they feed their citizens through education and state controlled media, knowing full well how easy this guy is to manipulate, and that he'll just believe and regurgitate. The best part is that it actually works.
I may not like him, but I can't fault Xi on that. He's smart and knows when he has the upper hand intellectually.
East Asia has an obviously very complex territorial history. You always see little spats between the Chinese, Japanese, and Koreans over "we invented [such and such ancient tradition]!" It's not surprising when the leaders of these countries try to spread this kind of rhetoric, but to see the freaking POTUS parroting this shit is beyond priceless.
Maybe some guy told Xi "This guy is a total moron. His stance changes based on whoever he last talked to. He repeats whatever you tell him."
And then Xi was like "Oh shit, I gotta try that lol"