Ah. That makes Kairi being able to put Sora's heart back together make more sense. The Heartless would destroy, "eat", the thing holding the feelings and memories together, not the feelings and memories themselves. As if feelings and memories were actual tangible things, anyway. That part is still kind of weird, but at least it makes a little more sense. The Soldier doesn't nod, since that would hurt, but they do make a little noise of agreement and understanding.

And then they say, about the scientists, with the kind of bland affect that says they're making a joke, "Sounds dumb."