Nero had not thought of a way to explain the silver light, so the best solution would be if he didn't have to explain it. Pushing Bael into the blood would be so easy, and there would be no fight to leave any traces. Even if there was an investigation, no one would be able to prove that Nero played any part in his demise.
Death by curse was the most common kind of death in this world, and regardless of how strong or well prepared he was, how could Bael survive a curse that even Nero could not face?
