The reason for wanting to involve the Empress Dowager is because in the entire Great Xuan Dynasty, there's probably no one with a higher status than that old lady. Don't be fooled by her usual indifference, only chanting sutras and praying to Buddha. The Emperor is very filial to her, as long as it's nothing outrageous, he'll go along with whatever his mother says.
Moreover, the old lady is also a righteous person. At least, the Jiang Family hasn't produced any detestable wastrels, which indicates a good family culture. Therefore, having her as a partner is more powerful than any Prince.
If successful, then she would be connected with the Crown Prince, Prince Yun, Prince Han, the Emperor, and the Empress Dowager. So no matter where there's trouble, she'd have a way out.
