First off, our own press does that on a regular basis. According to your assertion, Ali Watkins should be in jail, right? Why ain’t she?
Second, Assange is not American and did not operate in US jurisdiction. Our laws no more apply to him than than China’s laws apply to us here.
Combine the two and it’s all but impossible to convict him of anything. Find the statute that applies, if you disagree.
Assange was working with a US spy. Our laws apply to him no matter where he is or is from.
Suppose A & B break the law but I chose to prosecute A but not B. Doesn’t relive A of having broken the law! Prosecutorial discretion its called! It may not be fair but it exists.
How long was Noriega in jail? Remember him?
We’ve done similar things for international drug dealers, international bank fraudsters, etc. You break US laws it doesn’t matter where you are if we want to make the effort to get you & succeed that’s your problem! Even Mueller laughably tried but he had precedent for acting. If we can lure a foreign intel officer here who we know has broken our laws we’ll charge him. Its been done but usually they’re not that stupid! Also the espionage act doesn’t make exceptions for civilians.