Before leaving the Sinclair Order Island, Linsley sent a message to Lucy and Ted, informing them of his departure. Once he was sure they knew, he felt reassured, confident in their ability to protect the island while he was gone.
Even if a Level 9.8 Overlord managed to discover the island through some unknown means, Linsley wasn't concerned. The Level 9.8 Devouring Whale Overlord wasn't just for show.
According to their plan, Ted would primarily assist the believers in spreading the faith, while Lucy would focus on defending the island in his absence. Lucy would only leave the island if Ted encountered an Overlord beyond his ability to defeat.
Even in that scenario, the Devouring Whale Overlord would remain as the island's protector.
In addition, Linsley had weaponized the Holy Spirit of Judgment. While not specialized for combat, it was still capable of aiding the Devouring Whale Overlord in repelling any powerful intruders.
