Vamos encarar, os Diggers estão em um canto apertado. Eles foram forçados a viver dentro de uma faixa populacional muito estreita durante séculos - eles só têm espaço / recursos para muitos sobreviverem, e se houver muito poucos, as probabilidades de sobrevivência também despencarão. Eles demonstraram ter um sistema socialmente coercitivo para manter uma população precisa:
More important for present purposes was to get a general understanding of the Diggers' culture, and why they behaved as they did.
The requirement for a steel-spined authoritarian culture was obvious. Any power structure one of whose main golas was to prevent humans from [reproducing with] each other at will had to be extremely formidable.... Structurally, culturally, it was very like a Bronze Age theocracy, but without any trace of God or the supernatural.
Qual é a melhor maneira de os líderes fazerem com que sua sociedade siga as regras e siga as regras? Para criar inimigos Quem são os únicos inimigos naturais? As pessoas que foram embora e que ameaçam voltar com mais números do que os Diggers:
At some point the Committee - which was what they called their ruling council - most have become aware that vast numbers of humans were living in space and actively prosecuting the TeReForm. They could simply have walked out onto the surface and sent out some kind of SOS at that point. Instead they had made a positive decision to conceal themselves, to hide their spoil dumps, to shun communication with the Spacers. The central question, then, was why they had made such a choice. Sonar Taxlaw wasn't much help in explaining it. When Ty or the others asked questions, she offered nonresponsive answers that told of a subterranean culture in which such things were never spoken of.
It was clear, however, that having made that decision, the Committee would have to explain it, justify it, and perpetuate it by painting the Spacers as alien mutants, and furthermore by cultivating a finely developed sense of racial grievance against the cowards who had run away and abandoned them.
(Presumivelmente, os Pingers recebem um passe porque também ficaram, têm números mais limitados e zero conflito territorial com os Diggers)
A "cultura autoritária com espinhos de aço" poderia razoavelmente esperar muitas reviravoltas uma vez que houvesse contato com (aparentemente mais numerosos) Espaciais - e quando há agitação, as pessoas no topo não ficam lá. Então, onde Stephenson explicitamente declara que a resposta não é conhecida, acho que se resume à cabeça dos Diggers, temendo mudanças e declarando um inimigo para manter seu pessoal alinhado atrás deles.Página 802 parece confirmar isso, falando do Digger que foi junto com os espaçadores:
"But you didn't..."
"Abduct her? No, she just tagged along."
Sensing doubt, or at least curiosity, from the Ivyn, Ty continued: "And more would do the same given the chance. The transition to surface life is putting their culture through a blender. Which is why their leaders are being so reactionary."
(as citações são das páginas 796-797 e 802 de Seveneves)