He ran away to the embassy in 2012 because he refused to take responsibility for his sexual assaults. In 2010 he hired Israel Shamir, an extremely outspoken antisemitic blogger, to help run Wikileaks, and a number of photographs show that they had been close friends for some time before Assange hired him. When he was confronted about this by Private Eye in 2011, he began spouting conspiracy theories about how the Jews were out to get him.
Assange is alt-right and has always been.
Assange being alt-right and the fact that he is going out of his way to leak material that improves the chances of the standard-bearer of the alt-right, Donald Trump, becoming head of state of the most powerful country on Earth are absolutely 100% linked together, and those links should be investigated.
Some information should not be public for a reason.
You're assuming that the goal is to expose something - that is, you're starting your argument with the idea that he's got some political agenda to achieve.
But he's stated that his goal is to weaken the powerful by making it so that they can't trust anyone to keep their secrets. In that context, any uncovering of a leader's secrets is work toward his goal.
You can argue that the costs of what he's doing exceed the benefits, but I think your claim doesn't support the argument you're trying to apply it to.