The whole Assange thing is kind of messy. No, he's not detained, but nor is he free to leave the embassy. In 2006 the UN's Working Group on Arbitrary Detention concluded he has been subject to arbitrary detention by the UK and Swedish since 2010. But in all likely hood he published leaked emails with the express intent to hurt Clinton's campaign in 2016, albeit possibly not knowing the original source. But its within mission of the wikileaks to publish that sort of information. He did seek a Russian visa, but the number of countries that have the currently political power to resist EU & US pressure for extradition is pretty limited.

So much around him seems to be politically motivated, both proponents and detractors. I think the chances that we have a full and unadulterated idea of what is going on is pretty slim.

So ultimately ¯\_(ツ)_/¯