Because they were related (see above), he did not take offense at her prophesying together with him, even though he was a more important prophet.
Zayd ahaa wanaajiyay horgaygee mana Si kastaba ha ahaatee, ku haminaya ma hubohadii ay doonayso in ay isaga guursato, sidaa Nabiga (Salla Allahu alihi wa Sallam) ma aysan ku cadaadin wax dheeraad ah arrinta.