Because, in his view, this Palace Master of the Myriad Laws Academy could not possibly do such a thing for free.
"You brat, is that really how you see me?"
The old man shook his head with a helpless smile. "What if I said I don't need you to do anything at all, and that I simply cherish talent, which is why I want to look after that little junior brother of yours?"
Chapter 3862