Subject to Section 1502, a parent may nominate a guardian of the person or estate, or both, of a minor child in either of the following cases:
(a) Where the other parent nominates, or consents in writing to the nomination of, the same guardian for the same child.
(b) Where, at the time the petition for appointment of the guardian is filed, either (1) the other parent is dead or lacks legal capacity to consent to the nomination or (2) the consent of the other parent would not be required for an adoption of the child.