Zhang Zhiwen hadn't been here for long. He arrived feeling quite heavy-hearted, but left with an even heavier heart. Aside from all the things he had been worried about coming true, Liu Hun handed him a big problem before he left.
The issue with Du Bai's father was a predicament for him whether he handled it or not. But he had no reason to refuse Liu Hun's request, which essentially served as an act of loyalty—a fact Zhang Zhiwen was well aware of—so ultimately, he had no choice but to escort Du Bai's father away.
For Liu Hun, aside from gaining a helper, the greater benefit was to bolster his reputation. This ensured that while he was in Beijing, he would face fewer trivial disturbances, thereby saving Liu Hun a lot of time.
