That single sentence settled it all.
Of course, the Emperor wouldn't say it explicitly.
Even if he felt tempted to say, 'Princess Zhenming, you're so attractive. I wish to take you as one of my concubines', he would absolutely refrain from saying it in front of the imperial concubines and courtiers.
Among those in attendance, most were veterans of the political game. They made their living by discerning the Emperor's intentions. Given a mere look or gesture from the Emperor, they could decipher his wishes.
Moreover, not only did the Emperor praise Princess Zhenming, he also rewarded her and begged her to stay.
Anyone unable to grasp this hidden meaning should quit their political career early.
Not only did the ministers understand, but also the Empress and a few high-ranking concubines. They were all perfectly aware that they were to have a new "sister".
And this sister was a princess from a neighboring country.