It was inevitable, though. The show was about coping with loss and trauma - Tofu living on would have just papered over all that and given a magic solution. Tofu helped Nut solve his own problems - he didn't do it all for him. Sort of like when your mother says "show me how to do this on the computer, don't just do it." Which I ignore and just do it or I'll be guilty of matricide. Real conversation:
"Turn it off, then turn it back on."
"What do you mean?"
Anyway, Tofu represented treatment for mental illness and depression - once Nut was "cured", his direct involvement no longer had a purpose - now he's anti-depressant medication as a teddy bear to hug.