Why is Grayson surprised at what maniac tells him about the beals?

Grayson is surprised at what Maniac tells him about the Beals because he learns that they have been struggling with their own issues of acceptance and prejudice. Maniac reveals the complexities behind the Beals' family dynamics and their experiences with racism, which challenges Grayson's preconceived notions about the family. This revelation makes him realize that people are often more complicated than they appear, prompting him to reconsider his understanding of the Beals and their situation.