Hmm. Ok.
The disease is what is splitting people on the issue. In one camp are those who see the benefits of the crystalline, which are certain connections with otherworldly things. Those afflicted who manage to live with it can see/hear/interact with things that no one else can. They are therefore acting as prophets, they know something is coming, and they want to recruit as many afflicted people as possible to help fight it.
The other camp wants to destroy the crystalline by any means necessary. They see the prophets as terrorists that are spreading the disease wherever they go, spewing lies about saving the world to cover up for their massacres. They're especially looking for Spook, who they only know by name and mask, who they believe is the ringleader.
Which brings us to the present moment. North is Spook's thought, meaning something to do with The Thing That Is Coming. He's found something important, something he needs to retrieve and secure in order to prevent The Thing That Is Coming.
The guy in the underground -- the crystalline one -- therefore isn't the real threat. If he dies, everyone in that underground will be afflicted. If any of the crystalline patients in those cots dies, everyone will breathe in the disease. Those devoted to abolishing the disease are aware of this. This is what Switch means by massacre waiting to happen.