That case is just plain BS
The kid was not on school property and had every right to free speech. The school had no atthority to take action due to the location. Just because he is a student there doesnt mean a thing. The school committee agreed that the students be let out of class and watch forfeiting any right they had over the students when they left the property.
If the students were still on school grounds the principal could of done that, but what he did was over the line.