I don't really buy it. The crime he was accused of by the US is helping someone try to break into a laptop. That's beyond most journalistic standards for conduct and a criminal act. We'll see what can be proved in court from here.
He is also being accused of 17 counts of breaching the Espionage Act with a maximum sentence of several lifetimes in prison. The conspiracy to break the CFAA charge was just the taster -- and I would argue that it was done tactically so that the discussion of Julian would be "he's a hacker not a journalist". If I was working for the DoJ that's without question what I would've done -- whether the accusations were true…
So I don't see the justification to prosecute him. Of course governmental data of the US isn't protected from non-citizen access. Why should it, these are the rules they themselves set. It is naive to think that governmental actors have an advantage at espionage. On the contrary. The most advantages has anyone without critical secrets.