If we had watched the video, we can easily make out the real reason. It is little difficult but it is obvious. It was actually indirectly related with Nihira exit and proving all those people wrong who are still saying there was injustice with Nihira and it was to prove Himani a better singer than Nihira. That is what HR proved in his lecture and emphasised so many times that if you accept Debo's result then Nihira exit was justified and Himani is genuine winner in girls, And their main target was ID and public like us. For us whether Debo win or not, but ijustice has been done to Nihira. This is the same HR, for him ID always had soft corner. He had fight with J-L for Joyeeta and see how HR treated ID. HR is actually back-stabber.
ID like us never accepted Nihira exit as fair, so the gangs hatched a well planned strategy of walk-out. In this walk out, contestants were fully involved whether it is Hema or Vinit or Himani. Plot was If Debo get maximum vote then all 3 would walk-out. And ID would definitely react and before all public HR gand will relate this walk-out to prove Nihira exit was justified. Guy please try to read hidden agenda. These 2 are very cunning, ID is nothing before them. HR is too cunning a person. He is a person who reached this position by using wrong thing not by music that is why his knowledge about music is very limited.