Wei Wuyin's actions had been the focal point of this entire event. All the Earthly Saints were observers, wanting to know how this mysterious figure was going to solve this seemingly unimaginably difficult issue. To their knowledge, there was no solution, even amongst Mystic-Earth grade Alchemical Products. While there were temporary means to stabilize the situation, the aspect of Soulspan was far beyond their means to solve.
If they could, wouldn't they be effectively immortal? But they weren't, they were shackled by that dreadful term 'Soulspan' and it was inescapable.
Additionally, they were reinforced by Tian Muyang's belief and Wei Wuyin's words regarding his origins, so they were deeply intrigued by his decision. Not to mention, Ma Sujiang and Ma Zheng had gone to Wei Wuyin, not the Alchemic Saints or one of the four Medicinal Sages of the Mystic Dao—the Shamans, so this likely meant they knew more than them. To them, this was Wei Wuyin's origins.