How much of Murphy was left anyway? He has a rudimentary digestive system, which probably provides nutrients to keep his brain functioning, but how much of it is a brain/human tissue encased in that skull and how much of it is a processor. He has a human face, but that's probably stretched over a metallic framework, like a Terminator. I think, at some point, what's left of Murphy's brain is going to age and go through cognitive decline, resulting in it being completely replaced by a computer. The same goes for his digestive system. There will probably be nothing left of Murphy, but a program that thinks it's Murphy.