The sudden fall of the expert's cultivation level wasn't a temporary weakness caused by instabilities. His existence had continued to destabilize due to the absence of core aspects of his law, and the exchanges with Noah's group only quickened that process.
Moreover, Heaven and Earth seemed to have no intention of fixing his state. Noah believed that the expert had gone rogue and was attacking them on his own since Sword Saint naturally attracted his existence, but he didn't know whether to expect something afterward. It felt strange for the rulers to ignore his group after what had happened, but he could also justify their decision to remain silent.