It is debatable if what he did should be considered Journalism. Lots of legal questions about how U.S. laws should apply to people not citizens of the U.S. Tons of questions about his associations and about the 2016 election specifically...
Still, none of this is a reason to isolate someone for years without a trial or access to legal counsel. If the U.S. is going to apply its laws to Julian Assange, it needs to apply the basic rights that come along with it. He deserves a right to counsel, a speedy and fair public trial by a jury, the right to not have his liberty or property taken from him without due process happening FIRST.
These are all fundamental things we should all agree on regardless of the crime you have supposedly committed.
This strange fusion of the entertainment, legal and prison systems will not stop at Julian Assange. It was done to Chelsea Manning. If it can happen to them, it could happen to you one day.
TLDR; People have deserved a speedy and fair trial in western legal systems going back to when the Magna Carta was written. Whatever is happening here isn't justice.