Google's classified Pentagon contract does not just expose Google's AI to military use — it reshapes who builds military AI going forward. The engineers who signed the open letter are precisely those with the deepest expertise in responsible deployment, model auditing, and safety constraints. Their departure — voluntary or driven by a workplace they no longer recognize — concentrates that expertise at firms whose entire business model is defense. A second commenter captured the structural logic from the opposite direction: "'Vital advances' meaning things like AI weapons. Actually taking care…