I didn't even realize he'd done this until I saw George at the end. I was like "Wait.. WTF happened to him?".
I honestly just assumed that Raiden had sliced past him, and only asked "are you sure about this George?" because he knew he'd be taking a risk. Not because he intended to mutilate him lol.
What I find most ridiculous about this is that, with the way the doctor was holding George, Raiden could easily have cut clean through his head and right arm without going anywhere near George. Hell, I could have done it better. With a bread knife.
Also slightly off topic: they had that bit in the VR demo where you had to cut through targets who were holding hostages.. Wouldn't this section of the game have been a perfect place to put that into action? As things stand it isn't used at all.
If u watch closely, u see that raidens arm exstension tells the whole story. I cringed!
The way I interpreted it; Raiden was so eager to kill the doctor that he simply didn't care and George had intimated that he wished he could be a cyborg like Raiden. Well, Raiden granted his wish and scratched his own itch at the same time.