Although Grandpa Sheng wanted Mu Qiqi to yield her position to Miss Gu, he had to repair his connection to her and Sheng Xiao before that—he wouldn't have a chance to reach Mu Qiqi otherwise.
Because he knew very well that the more heavy-handed he was against Sheng Xiao, the more likely he would retaliate.
Naturally, he shouldn't be offering an olive branch to those two for no reason. Given how intelligent Sheng Xiao was, would the old man not be directly letting him on his plans and affording him to exploit it?
He must set the scene meticulously if he did not want to arouse Sheng Xiao's suspicions.
Moreover, he could repair relations with them while connecting the family to Miss Gu at the same time.
Meanwhile, Sheng Xiao had called home his second brother to be groomed as Huang Yao's leader. His excuse would be Jing Yun's return to the Xu family, and he needs someone capable to share the workload.