It’s self preservation. I think that’s pretty evident. He knows what Russia, China, N. Korea, Iran, Saudi Arabia, etc. are willing to do to protect their info. And lets face it, assassinating Assange would be news for 2 days and it would fade after that. He’s nobody’s hero, just a tool. There will not be mass protests, or lines of mourners. Just “Whoa! guess he fucked up!”