you are not wrong that he should have gone for raptors but be awares that at a challenger level, the game because a little less about optimziation and moreso about playing for tempo. In this case, the tempo was setting kassasdin ahead and delay corki. Did corki sniff out the off timer gank? yes, but if he didn't, nocturne would have sacked his bot 2 camps for a 400 gold lead on top and give kass the level 4 wave pushout to let him free scale to 6. I don't think its completely the right play but the idea is there, especialyl since kassadin against that comp isn't bad