Then kush could be mafia but it's not sure, and suddenly there are 3 targets in rayn, balla, kush and only 2 lynches. in this case the correct play is actually to lynch not-kush. It will be 3-1 going into night. Then we tell kush to shoot the other target. If kush is town the other target dies and town wins. If kush is mafia then there will be no vigi and we lynch kush.
the reason it wouldn't be sure that kush is mafia is that the last mafia knows his only chance is to kill the person kush is roleblocking in the scenario that kush is not mafia in order to stand even a miniscule chance. however the vigilante plan deals with that and regardless everyone gets confirmed/dead.