Let's look at the facts...
1. His own engineering teacher "suggested that he not show the invention to other teachers." He should have listened, but...
2. During his English class the case made beeping noises. Not smart bringing it to English.
3. When questioned, he didn't explain what it was all about, and was described as playing "passive aggressive".
4. He calls it an "invention", but a digital clock in a case is not an invention. He's 14 years old, not 8. There's nothing inventive about it.
5. Admitted in the video he chose a "simple cable" to lock the case so it "wouldn't look threatening". So let's be clear, he did think about the possibility of it looking threatening, and his own teacher warned him about it.
Are the pieces coming together for you?
if he's smart, which apparently he is, then he should move on from clocks in cases to something that approaches an actual invention.