Who are we to tell them they can't sell the only thing they have of significant cash value, because some people think it's bad? They could automatically go to the top of the list for receiving a transplant if their remaining organ ever fails. As well as saving lives, this would prevent the problems associated with an unregulated black market.
Islamic State militants blow up ancient Arch of Triumph in Palmyra (Reuters)
from the article: Israeli MDs harvesting organs for international trafficking ring