he recognizes the Nicene Creed as a defense of the Church’s understanding of Christ’s divine nature against a theological innovation.
That’s about as near to the exact opposite of what Hart said as you could possibly get. Hart’s whole point is that Arius represented the traditional view and Nicaea was the innovation. More than that, he says that this fact is well known among scholars even if it may be surprising to others. (The comments of many other scholars on the subject bear this out - Paula Fredricksen, EP Sanders, Geza Vermes, Adela Yarbro Collins, to mention a few.) You can waste as many words trying to get Hart to the say the opposite as you like but it doesn’t change what he says. It’s a pointless exercise.