Reprimanding a student is appropriate as long as the teacher does not yell and holler right in front of a large group of students and teachers, with the intention to derogate and humiliate the student. When has the teacher crossed the line is subjective.
Some teachers have a pleasant, easy-going disposition, while some are stern, nitpicking and immature. Whether or not the reprimand is justified depends on the judgment of the other students and teachers. The case must not be reviewed only within the disciplinary committee, or else the school will have a bad impression.