NEW YORK A U.S. health boss's murder sparked a torrent of online misinformation and calls for violence against other executives, suggesting a failure of social media moderation that analysts fear could translate into real-world harms. The posts, allowed to spread unfettered across tech platforms, came in the wake of the shooting of UnitedHealthcare CEO Brian Thompson in New York on Dec. 4 and lay bare a Wild West internet landscape that is largely bereft of guardrails. "As much disagreement as