In Louise Erdrich's "The Red Convertible," why does Lyman keep the car parked while Henry is away?

I believe that in Louise Erdrich's short story, "The Red
Convertible," from her collection entitled, Love Medicine, Lyman
keeps the car parked when Henry is away, so when he returns it might help his brother
feel as if not much has changed at home while he's been at war, and that there is still
a place for Henry away from the battlefield.

Unfortunately,
when Henry comes home, he is a different man. Lyman messes up the car to give Henry
something to do (by repairing the car) when he returns. Lyman is anxious to get Henry
out of the house and away from the TV, where his brothers spends almost all his time.
For all of Lyman's attempts to make things better for Henry, including his "treatment"
of the convertible, some things are irretrievably lost to us in the face of the
hardships life throws at us. For Henry, there really is no going back home, and sadly,
he can see no way to move forward, either.