I don't remember Walter seeing PH. But it would make sense giving his history and knowledge of the cult. However, I don't recall him ever feeling the need to be punished for his sins of murder. I know he felt guilty when he killed the Billy and Miriam Locane, that's why they never turned into ghosts like his other victims. But did he want to be punished? Giving he see's what he's doing as a way to see his mother on an unstoppable mission, I'd say, no. So how did he see PH then?