From what I can see, the real problem was that he leaked confidential information to the outside world. Unless we can prove some harm to the consumer or the shareholder, I don't see why anyone outside of the company should care.

I still see this as a contractual matter. If his employment contract strictly forbade him from doing this (and it might very well do so), then that's grounds for termination. Just like how copying homework could be grounds for suspension from school. But still a different effect on society than stealing.

Another thing to consider: he's making the company management look bad. The smart thing to do would be to promote him for his smart thinking.