I agree that it is a big surprise that he was given methadone and not a morphine pump.
My mother died in 2001, and she had a morphine pump for pain. My nephew died last October and he had a morphine pump and was given anti-anxiety drugs to help him pass very comfortably. My mom died in a hospital unit for one term care. My nephew died at a hospice wing of a hospital. 
Neither my mom or my nephew were going to get addicted as they had only hours to live and those hours were as pain free and comfortable as possible. They died with human dignity.