How do you hack something without discovering a vulnerability? Assuming that there are no known vulnerabilities.

Ok, technically you are correct. Good job. What I meant is he wasn't hacking benevolently to discover vulnerabilities to promote world peace and economic development for poor orphans and endangered species.

But what exactly is different between this guy and some benevolent hacker? According to the linked article, the storyline sounds pretty much like the old "someone hacks a big corporation and tries to inform then, but gets ignored or accused of crime".

The difference is intent.

There is no way for us to know the intent. Shouldn't we just look at the actions? Was the stolen data misused somehow in this case? The article does not say so.