Maybe Yubaba is keeping him frozen in a childlike state her own nefarious reasons?

Or river-god-dragon lifespans and ageing may just be on a totally different sort of timeline...

*ponders*

This is, needless to say, an utterly gorgeous set of masks. And somehow I don't think I ever noticed before just what a puppyish nose he has in dragon-form. Now I want to grab him by the ears and kiss the top of his head like I do with my pittie girl.. :)