The child born outside the bond of marriage is not the father`s child as per shariah. No inheritance, no family ties and no respect as father found in books. The holy prophet SAW said that the adulterer merit only stones to be pelted on him. Nothing more.
But he is the means for him be born. As such fuqahas have expressed that the daughter born from adultery cannot marry the adulterer. Because he is the means for her to be born. As such there is a kind of consideration on that. But he is a human being and merit kindness as any human being. Even if a non muslim is in difficulty, we need to help him.