From an economic POV it certainly would make sense.
The thing about people buying art is they generally don't want to buy art that evokes negative feelings. With your friends work you can see there's a lot of emotion going into his work that on the other side provokes in a viewer feelings of being stuck in a rut, of being in eternal limbo. I don't know about you but I wouldn't want that on my wall.
Now of course going all loveydovey and happy would absolutely not work with him. But his material of choice "wood" can easily carry connotations of new life, of rebirth. I think the piece "Earth Mother" is very strong in that regard and thus stands out from his other work.
you have hit on one of his big motivators, that of reclaiming discarded wood and giving the wood itself new life. This maybe isn't represented as good as it could be because of his subject matter. I have spoke to Peter in length about his work and have even expressed the same concerns that you have. As you say loveydovey wouldn't cut it at all with Peter but maybe the idea of rebirth and hope might be explored more. Mother earth does indeed have that kind of power.
Are you an artist yourself? You certainly have managed to tap into his art really quickly