A legal threat from investor Mario Gabelli was a "major factor" in this week's implosion of Shari Redstone's 8billiondealtomergeParamountGlobalwithits"Mission:Impossible"productionpartnerSkydanceMedia,ThePosthaslearned.WhenRedstonemadeasurprisemovetopulltheplugonthedealthisweek—justbeforeaParamountspecialcommitteewaspoisedtovoteonit—shewaslookingdownthebarrelofa100 million-plus lawsuit from Gabelli over the deal, according to sources close to the sit ...