There are important steps to resolve a potential bomb situation, and several important things to not do.
If you were to discover a bomb at a venue where there are children, here is Step 1, Clear The Area:
You should not keep the room occupied while you pick up the suspected bomb and play with it.
Having evacuated the room or area, you should make sure to keep the area clear and the suspected bomb.
Step 2, Keep the area clear:
Under no circumstances should you pick up and carry the bomb through an occupied building as if you were showing off a fish you caught.
Step 3, Call The Bomb Squad:
Given the basic, correct responses to the discovery of a bomb, and that the Irving school that had someone arrested for exposed electronics made every worst decision they could manage if they really believed the electronics were a bomb, the only logical conclusion is that they lied about their belief. Whether it was religious or racial bigotry, or just assuming that anything that breaks their routine is dangerous because public educators are brick-stupid, it doesn't matter.
What matters is that the claim that the school or the police genuinely believed there was a bomb is bull.
And the conspiracy claim that the student's father built the clock out of stripping off the casing of a 1970's vintage clock bought on eBay (with no proof at all) in order to spark an incident doesn't speak well of public education, if all it takes to cause a fake panic is stripping the casing off of cheap electronics.
Lastly, the claim that, because the student is Muslim he is therefore guilty, is simple bigotry. The religious victim group used to be Jews, Mormons, and Catholics at various points in history, with mostly the same histrionics as today. It's as much bullshit now as it was then.