He is being brought up on hacking charges. He committed a crime.
From your linked article:
Is one failed attempt to crack a password really enough to embroil Assange in a felony hacking case? "For the CFAA, unfortunately yes," says Jeffrey Vagle, a former University of Pennsylvania law professor and current affiliate scholar at the Stanford Center for Internet and Society. He points to a long history of using the overly expansive wording of the Computer Fraud and Abuse Act to hit hackers accused of even trivial acts with serious charges. "The fact that his involvement is de minimus isn't enough to stop an indictment, because the CFAA is just so broad."
So this is based on an clear overreach of the wording of the law.