Or don't do that, either, because it is not right to assume people are going to pull off bomb hoaxes. (Doubly so when the only real reason for the suspicion is skin color.)
Yeah but you also don't want to be the admin at a school with a bomb where there were "signs a student was creating bombs before he went ape shit". I agree with the color statement, but not addressing the issue at all can be just as bad as an overreaction.
Obviously someone thought there was a sign, even the teacher told him not to show it to anyone else outside that class. I think saying that a homemade clock isn't a sign is greatly underestimating how the news is capable of skewing things to screw people over.
I looked at the pictures. Any adult with even the slightest understanding of how a bomb must physically work--like, "have something that can actually explode"--should be so utterly certain of its purpose that your concern trolling should horrify them.