Of course that Buddha is a natural human. What else could they be? That's the whole point -- to accept it and not desiring to be something different, not rejecting one's human form. But also not clinging to it. Thus, as you aptly pointed out, there can be no talk about emotional attachment. The grief/sadness simply washes over the enlightened Buddhist, and then they act, if they act at all, just with the knowledge of the feeling, but not in order to alleviate it.