What does it mean to lament? It means to express passionately your grief. It is crying. It is mourning. It is grieving. Sometimes it's all you, or others, can do.
David is a prepper with a heart and he sorrows for those who have not heeded the call to prepare. Those poor souls who have not put food and supplies away in case of a disaster are facing famine and disease from a cyber attack that has taken the electrical grid down. David has other laments, things that only a prepper knows or can share. Protecting his own food and his humanity is one distraction; the other is his concern for people who are forced to labor in public works projects in order to receive food.