Yes, assuming post-Everett quantum mechanics, our continued existence needn't be interpreted as evidence that Mutually Assured Destruction works, but rather as an anthropic selection effect. It's unclear why (at least in our family of branches) Hugh Everett, who certainly took his own thesis seriously, spent much of his later life working for the Pentagon targeting thermonuclear weaponry on cities. For Everett must have realised that in countless world-branches, such weapons would actually be used. Either way, the idea that Mutually Assured Destruction works could prove ethically catastrophic this century if taken seriously.