Titan is not a protection against National Security Letters, it's a protection against hacking. NSA, China, and Russia have all successfully hacked Google or Go

Titan is not a protection against National Security Letters, it's a protection against hacking. NSA, China, and Russia have all successfully hacked Google or Google accounts in the past. National Security Letters can be challenged in court. You fight legal attacks with legal defenses. You fight technical attacks with technical defenses. Although swapping them does give rise to some interesting techniques. Legally challenging technical attacks can be tricky due to jurisdiction, but it would be cool if Google could at least try suing the countries that attacked them. Technical defenses against legal attacks can also sometimes work, by building systems where the company themselves don't have access, such as E2E crypto.