At this point, the ministers simply thought the Emperor did not want Shen Nian to hear about Chang Sheng's treason from elsewhere, so he was coaxing and reassuring him.
Later, when they finally realized the true nature of the relationship between the Emperor and Marquis Zhenbei, one by one they would feel that they had been utterly blind.
How could today's exchange between the Emperor and the Marquis have been mere mutual flattery? They had been openly speaking words of affection!