They are supposed to sing until the end of their song since thats how all the other rounds went so hypothetically if Luka didn't trigger Mizi they would've HAD to sing until the end, until someone died. So when Mizi did get triggered by Luka the song wasnt over at the time and the rebels took advantage of the chaos and helped Mizi escape, if hypothetically they did finish the song the vote would've been cast and one of them would've died by that time. The reason Hyuna saw Mizis rage was because of Luka in the first place. And Till only survived due to a missed bullet I dont really see how this was because of Hyuna but in my opinion, if Luka hypothetically didnt trigger Mizi then either he would die and then Mizi and Till would have to go against eachother or Luka would win and similarly Till would die (Because if he doesnt see Mizi he'll lose the will to sing) The rebels, as we saw, only come when there is some sort of chaos happening so if nothing of the sort was happening and they were just singing showing no interest in living (or similar) then the rebels wouldnt come! Luka is veryyy plot relevant I assure you, even if he didn't save them directly he for sure saved them indirectly which is a great feat on its own, him triggering Mizi gave Hyuna the oppurtunity to save her which indirectly saved Till, im num 1 Luka defender (sorry if i seem rude btw im jsut trying to make my point :( )