I think this is the correct take. And until we have an AI Hiroshima it’ll be difficult to get the international community to work together. It’ll take rogue AI (or AI-powered group) disabling a significant world power before everyone comes to the table. Otherwise, it just looks like MAD and the equilibrium holding to the powers that be.
It wasn’t the shock of Little Boy that ended the war. That was just a final chapter of a 10+ year journey of horror, despair, and destruction, and the impact of Little Boy cannot be considered outside of that journey.
Europe had been destroyed by June 1945, and yet the empire of Japan continued to fight.
If that pattern holds, a single malicious AI substantially disabling a single world power won’t end the AI race. Participants don’t learn by the defeats of others.
If you’d like to apply a metaphor maybe the 10+ years of world war is more appropriate, after which basically every participant save one was exhausted.