If the victim was unresponsive and the regulator not in his mouth, then sending the victim to the surface by himself makes sense, especially if the buddy knew the other two were up there waiting.
First rule of rescue - don't make two victims out of one.
Book says to get an unconscious victim, without reg, to the surface as fast as it is safely (for the rescuer) possible. We just don't know if the guy had a reg in his mouth, or not.
Anyone see why it would be wrong, if the assumption that the regulator was not in the victim's mouth is correct?