MJ--Someone who is in war--involved in killing and seeing killing--is not to be judged by our normal standards. If he behaves in this way, it's protective. If that's what he needed to do to protect his mentality after seeing many friends die, let him function as best he can. To say "He should care no matter what" is to not recognize how death and war affects one while they're in the middle of it. After war, he has the responsibility to do what's needed to be healthy, but during it, absolutely no judgement is to be made about whether he should 'always' care about those around him. Tho he may make an effort to not care for them in the sense of getting to know them on a personal level, as soon as they exited their barracks and went to the war field, he cared for them by protecting them from the enemy. That's a good kind of caring even if he made no effort to talk to them about where they're from and what their hobbies are.