they believe he is dead and the headmaster is preserving his body with magic (which is true), but he's not completely dead yet. The students think this is inhumane and disrespectful behavior with a students dead body. I think they think his death is being unjustly covered up by their headmaster.
It's because they are delaying the report of the incident to the authorities. If you we're a victim and the suspect of the incident isn't dealt with, you will get mad. So the students decided to take action themselves. If it's reported, Shirone will be declared as dead by the authorities and be buried.
Ooh, I thought he did something bad, thx
Why do they want to take him?
I have to reread it but not knowing it will drive me to insanity, please help