I thought those panels were the throwaway joke.
V, don't forget that Philippe is in
therapy for something. So there's more to him than just being 5.
Well, I think this gets back to the Achewood Hypertime thing. Philippe clearly used to be a retarded adult in therapy for something at the beginning of the strip... but in the beginning of the strip, the Underground didn't exist, the alive stuffed animals couldn't get pizza, and Ray had an owner. In the current version of the universe, Philippe appears to just be 5, although he may be in therapy for his many traumas.
(Speaking of which: is Franky dead yet? I sorta lost track.)