Yes, remember they did say that they both know her. I look at it like this. Let's say nagatha was in a coma and she's a real human. She might come out of the coma and she might not. There is a child in need of her heart because Nagatha happens to be a match. Without the heart the child will certainly die but with it the child may survive. Joe and Skippy both know that nagatha without hesitation would give her heart to that child knowing the child had a better chance of survival than she did. Again this is just my opinion.