Granted, people should be far more aware of what they pack when getting on a plane, and TSA wants people to get "a wake up call", I don't think this is going to have that effect. Unfortunately I think the wake up call that will come from this is, if you're in the same situation continue to conceal it or dispose of it secretly to avoid this nonsense.
A more reasonable approach, considering he voluntary reported the mistake would have been too confiscate it for the duration of the stay and then return it upon leaving the country ensuring it's packed properly for air transport.