well judgment aside, they should be more careful. you have to be considerate of the world we live in now. muslim terrorists make front page news pretty regularly, so as a muslim you should want not to be associated with them.
i am a white person, so if i don't want to be associated with racist cacs i need to think twice about how i present myself. if i all of a sudden shaved my head, grew out a thick beard and got me some confederate tattoos... i imagine there might be a few ppl out there that wouldn't feel comfortable around me.
and best believe if i were a teacher in that school and i saw a young brown skinned boy - possibly muslim - walking around with a strange briefcase, and he was being purposefully vague, and he was being uncooperative... you're damn right i would be suspicious and afraid.