Is it permissible for my uncle to take back his divorced wife for the third time, knowing that they have a child, and does the Almighty's saying, "And their husbands have a greater right to take them back," apply to this case?

If the maternal uncle divorced his wife with less than three pronouncements of divorce seven years ago and wishes to return to her, then a new marriage contract must be drawn up, fulfilling its pillars and conditions: a guardian, two witnesses, and a dowry. As for the verse mentioned in the question, it is not applicable as evidence here because it specifically pertains to reconciliation (رجعة) before the expiration of the iddah (definition) (waiting period), and her iddah has already expired. If he divorced her with three pronouncements, then she is unlawful for him and will not become lawful for him again until she marries another husband, consummates the marriage with him, and then he divorces her.