In regards to why
Peggy and presumably
Cam Clarke went uncredited, I don't think it was a personal choice by the actor himself, but more than likely it was
Bang Zoom!'s decision on wanting to stay true to the Japanese voice actor credits of
Hunter x Hunter on it's later episodes, which would explain why Issei Futamata (Peggy's voice actor in the Japanese version) was credited as ONLY the Narrator and NOT "Narrator/Peggy"