He's had his concessions and his delay. I don't see why he shouldn't face justice in the US now, assuming the US justice system can supply it.
The reason for particular caution in this case is that the United States is an interested party. It thinks Assange used a technological platform deliberately to cause damage to the US, whereas Assange says he merely provided a platform for speech. Both things can be true at the same time, more-or-less. But if the US is itself a partisan actor, how can it also be impartial?
I can certainly see why the US might wish to incarcerate him. But justice might be seen to be done better through a neutral court, whose national interest is not involved.
A second issue is whether he has any special obligation to the US in the first place. I hate Putin's regime, but I wouldn't put US right wing talking heads like Tucker Carlson in jail in Ukraine because they say supportive things about him. Is something similar not true for the Australian Assange vis-a-vis America, if indeed he was malicious? And of course, Assange was not expressing opinions. He was providing a vehicle for speech. Like (and also unlike) Google.
Interesting conversations about free speech limits, which do actually exist even in free societies like the US (eg you are not free to copy things that belong to others, you are not free to corrupt minors, you are not free to promote sedition or to transmit state secrets).