Remember the US did not seek extradition for the 2013 leaks he coursed Chelsey manning into getting him, it wasn't until he conspired with Russia to interfere in the 2016 election that the US decided to seek extradition.

Page 44 of the Muller Report In order to expand its interference in the 2016 U.S. presidential election, the GRU units transferred many of the documents they stole from the DNC and the chairman of the Clinton Campaign to WikiLeaks. GRU officers used both the DCLeaks and Guccifer 2.0 personas to communicate with WikiLeaks through Twitter private messaging and through encrypted channels, including possibly through WikiLeaks’s private communication system.

https://www.cnn.com/2019/07/15/politics/assange-embassy-exclusive-documents/index.html Despite being confined to the embassy while seeking safe passage to Ecuador, Assange met with Russians and world-class hackers at critical moments, frequently for hours at a time. He also acquired powerful new computing and network hardware to facilitate data transfers just weeks before WikiLeaks received hacked materials from Russian operatives.