Su Rong understood that the Emperor seemed to very much wish Zhou Gu to stay in Nanchu, better yet to claim her as his queen.
By his view, it would very much benefit Daliang. After all, Zhou Gu was born to the Duke Residence, with all her family in Daliang. If he could harness her, then he could tie Nanchu tightly on Daliang's leash. Though her foster family was in Daliang, for the emperor, it wasn't enough. After all, those people were simply her adoptive parents and siblings, without any blood connection. The emperor and the crown prince, who had a kinship with her, had not watched her grow up from childhood, and the emperor knew that there was no affection strong enough to tether her.
If one day, she became overwhelmingly ambitious and turned against Daliang, he believed it was not impossible.