See http://www.ca9.uscourts.gov/ca9/newopinions.nsf/11BBADA028A095D58825712D00016761/$file/0335701.pdf?openelement where those concerns are discussed.
The fact is that the government has to demonstrate the school had a reasonable and good faith belief that the students' actions would harm the good order of the school. On the basis of what else the school was allowing to go on that day, the court expressed extreme skepticism that the school's efforts were either reasonable or in good faith.
See #52.
On my part, however, the students are under someone's jurisdiciton at that time. They are involved in a school activity that involves moving the scholastic focus to a different location....that of the passing Olympic Torch. During that event, students unveiled a pro-drug banner and disobeyed a directive from the controlling authority.
They are entirely wrong. The principal is entirely right. .....So long as they stay away from a religious sensitivity argument, and focus on the disruption caused by the pro-drug message.
I'm not sure if they can introduce new arguments when it gets to the Supreme Court level, or if they can only improve on their original avenues of persuasion.