I was skeptical until i saw the picture. If there was no other context it looks pretty suspicious. If you left this thing unattended at bus stop you bet there would be a bomb squad on it.
But now that we are all familiar with pencil box clocks, one could easily mimic this design for a real bomb. A block of c4 would work nicely as the transformer core.
It does not "look pretty suspicious". You suspect it. Suspicion is a process that happens inside your head, and is not intrinsic to the object.
We can agree that the device would look unfamiliar to many. But that people treat unfamiliar things as scary is up to them.
As I mentioned elsewhere, the biggest recent bombing in the US left a backpack behind. Others have used briefcases, trucks, and even a Christmas present:
So if you are serious about security, then you should call the bomb squad for ordinary objects left behind at bus stops.
Of course, nobody getting the vapors about this incident is serious about security. If they were, they would not have carried Ahmed's device around the school building. If they thought it was a bomb, they would have stopped touching the device, evacuated the area, and called the bomb squad.
The actual problem here is not Ahmed's clock. It is teachers and administrators who think their irrational fears are far more important that kids' educations.
I mean, you're right that if you left it unattended at a bus stop the bomb squad would show up. But the same is true of a cardboard box or a backpack. Nearly anything looks suspicious if you leave it sitting around. That's not a reasonable criteria for "resembles a bomb," especially when it wasn't left sitting around.
But now that we are all familiar with pencil box clocks, one could easily mimic this design for a real bomb. A block of c4 would work nicely as the transformer core.