These students should be happy they were only expelled:

Korea University permanently expelled seven students on Wednesday as a penalty for detaining nine professors earlier this month.
Korea University is one of the top three universities of the country. In protest against the expulsions, about 100 students, including those who received the penalty, held a rally yesterday, cutting their hair.
In Korea, cutting one’s hair in public is a sign of strong protest.
On April 5, the students detained nine professors for about 17 hours on a stairway of a school building, calling for the university to grant students in the college of health science the right to vote in the students’ union.

They should have been charged with kidnapping or a similar charge.  If they would have just kidnapped and beaten some USFK soldiers and then forced them to make coerced statements on national television supporting their cause, they would have faced little or no punishment that way.