Taking on a disciple is a big deal.
A disciple isn't just a student. In the East Asian culture circle, whether it's Chinese or Neon, disciples are like children, inheriting the master's legacy. They're deserving of the master's full attention and resources for cultivation. As for students, like at Far Moon, Xia Yu just fulfills his duty. It's up to the students whether they listen or learn, unless they belong to the few at Polar Star Dormitory; otherwise, he never goes out of his way to tutor them individually.
Liu Ying is excellent, but in such a big matter, Xia Yu didn't make her kneel down and offer tea on the spot.
Considering Xia Yu's perspective, taking her on as the first disciple or senior disciple right away, he feared his reputation might actually bring trouble for Liu Ying.
