I had to rewatch that part (the sound was fuzzy so I had to really turn it up) and you're right. I had thought I had heard "Kent didn't argue strenuously" and was released because he inadvertently chose Zatanna, when in fact he did and Nabu finally had enough. After all, he already lost Kaldur and Kaldur did use the mystic arts though not on the same scale as Zatanna and Zatarra.