Or they could have just not cared. Distracted by the high intensity fights they were watching elsewhere. I have the feeling that the Bleach universe isn't nearly so active with fighting without Aizen. Given that they have shinigami patrols of mid rank, i doubt you're seeing very many 'heavy hitters' fight at any one time. It was stated that most of soul societies strength lie in the captain, so we can assume that most hollow and shinigami are actually quite week. To make an analogy, for the scientists it'd be like watching little kids play basketball, then watching the globe trotters play. Even if the 'little kids' game is still going on, you're going to be watching the globe trotters.