I agree with his choice to welcome the younger sibling back home. He was clearly hurt by the son's decision to leave and as a parent -whether mother or father- the fear he must have had when the younger son left had to be great; his youngest child going out into the world all alone to places where he -the father-couldn't protect him from whatever evil that was out there.
His choice to welcome the younger son back is one out of love, it shows that he cared very deeply for his son and that he was glad he was save and back at home where he could protect him and help him grow more as a person.
(This is my personal opinion, you can use it or expand on my ideas. Hope it helps!)