In The Road by Cormac McCarthy, how could one argue that the man is both exiled and enriched?It isn't making sense to me how exile can be...

I don't know that I would have used the word "exile", but
I think I understand what they are driving at here.  The man and his son are headed for
the ocean, not knowing what they will find.  They are that desperate to just head in the
general direction of the ocean down The Road.

Their former
life, with the man's wife and the boy's mother, is permanently gone.  It is too
dangerous to live in their former home, adequate food and drinking water is scarce, and
they are quite sure that if they stay where they are, they will die.  So the exile is
from a life the man once knew, to a life of danger and the
unknown.

This alienates them from everyone else.  There is
no one they can trust, and humans have been reduced to the struggle for mere survival. 
However, with few worldly possessions, and their existence revolving around survival and
reaching the ocean, they are also liberated.  Everything is the love between the man and
his son and their desire to look out for and protect each other.  Everything is their
relationship, from the beginning of the story to the end.  This is
enriching.