@Oculunus : Because his 'strength' is in his heart, not his combat prowess.
Reminder that this is a man who literally saved an evil god through a "you're not alone/you're not a bad girl" hug.
I do wonder though,even if Noir somehow kill him as per the wish, would the Gods be like "look at this exemplar of virtues, let's UPGRADE HIM TO A GOD (and also would let him 'marry' Alterna on equal standing)"
Or will Noir lose her evil god status by for the first time refusing a wish (with some Kane's encouragement), making her go from a 'nameless goddess' to one with standards in what kind of wish she grants (i.e. take after her 'dad' in only granting non-malicious wishes)
Then again an anti-climatic 'good girl hug'working one more time would be...amusing for me.