As a parent, can I see the list of "items... that are prohibited"? I'd be pretty shocked if "clock" is actually on there.
Sticking to the line that something was a 'bomb hoax' keeps the responsibility with the accused: they shouldn't have perpetrated a bomb hoax; not we shouldn't have over-reacted to an innocuous object.
Then again, this is Texas.
"Though city prosecutors eventually concluded there was no ill intent involved in the placing of the ads, the city continues to refer to the event as a "bomb hoax" rather than a "scare." - https://en.wikipedia.org/wiki/2007_Boston_bomb_scare
The boy's father is from Sudan and is well known for being outspoken against anti-Islamic policies. To an unworldly south/midwesterner that spells "potential terrorist". It's not too much of a stretch to see that diagnosis extended to the son.
The school admins reacted as stereo typically badly as they could have hoped. It should have been assessed quickly and immediately removed from the school. Instead it just got stupid quick.
So this father will now get images of himself with his son with our President. We get some immediate attention to the horrible plight of Muslims in America (there isn't any horrible plight other than some people don't trust them)....
Remember the Aqua Teen Hunger Force "bomb" scare in Boston? The city rigorously pursued legal action to spare their police department the embarrassment of having wasted millions of dollars carefully dismantling DIY Lite-Brites.
No but embarrassment may explain quite a lot of it.
Calling it a hoax bomb is ass covering by shifting the blame to the person who happens to be the only adult in that bumfuck town's government.