They’ll probably apply some brutal torture first - to get names of other student leaders - then throw him out of the top floor of the men’s dormitory.
If they kill him he’ll become a major martyr for the students. They’ll try to convince him to cooperate via threats to his family etc.. The mullahs are living the good life in Iran, they will not give up power peacefully. Only when their backers are eliminated with they scurry out of the country like rats leaving a burning building. If that happens Saudi Arabia will make room for them and provide them with a sanctuary. Think not? Wait.