LAN YU was in an extremely good mood. How could he not be when everything was just going according to plan? Truthfully, he was a bit worried that the real 'Noctis' would go off and explain himself to everyone. After all, if he made it clear that it was not him being mentioned on the article and someone corroborated that, the people from Yunyue for example, then his name would easily be cleared.
No matter how much people called team Yunyue as the 'fallen champions', its three remaining original members still had good reputations individually. If all of them supported Noctis' statement, then it wouldn't be long before they reversed all the effort he put into this.
If he tried to fight that with more water navy, it would just be counterproductive. People would definitely notice that something was amiss.