Talk: Gardens of the Moon/Chapter 22

Earlier Quick Ben explained to Whiskeyjack that the reason the attending mages looked ill (and the reason Quick Ben had a headache) is because no one is opening their warrens because it would signal to Raest like "a beacon on fire" and so Raest would be able to take enslave lesser mages. So why did Mammot open his, or was he enslaved another way?