Incomprehensible nuance in the plot of the 46th mission (spoiler) (Metal Gear Solid 5: The Phantom Pain)

Here everyone says that the person who got the face plastic surgery is a doctor, what other doctor I don't understand, it's like one of the surviving BB soldiers, isn't it? Or is it the same medic from the mission where we were in the isolation ward with a bunch of corpses? But how then could he be there if we were playing for him at that moment O_O?