"An annuity buyout for active participants that will remain employed is not the type of event that the statute or regulation were designed to capture. Though the annuitized individuals will cease to be participants in the Plan, the change in status does not result because of a workforce reduction event of the type contemplated by PBGC's regulations, such as 'a reorganization or restructuring, the discontinuance of an operation or business, a natural disaster, a mass layoff, or an early retirement incentive program.' "  MORE >>