I used to think this before I understood that there are many people above him that need to be taken down. He is a lieutenant. We want the General. Keep him alive, force him to give up his handlers. He took a deal, and is on our strings now.

Consider that all his handlers want him executed as well to hide evidence of crime. Dead men tell no tales and sign no affidavits. This is how they stay hidden, by executing those that know.