I reckon there's at least three different issues at play here. And on reflection I can divide one of them up into several sub-issues as well.
1) Should Assange serve time for breaching the Espionage Act? Obviously not, leaking US state secrets is definitely a good thing, some people might not consider it strictly "legal", but then some killjoys would probably tell you that it's illegal to shit in Sunak's lakes.
2) The Sweden rape allegations. Been gone over quite a bit on here and elsewhere, hopefully we can all agree that it would've been a good thing if he'd gone to the Swedish courts and resolved them one way or another, since he didn't do that it's hardly surprising that there are some people who refuse to support him on those grounds.
3) More broadly, is Assange someone we should be making it a priority to support in whatever way? I would say no. Yeah, he faced (espionage) charges that he shouldn't have had to serve time for, but so have a lot of people. As mentioned above,
Assange's support of Trump during the 2016 election puts him outside of any kind of liberatory political project as I understand it. It's always bothered me that Assange gets so much more support than others associated with wikileaks and the like did - admittedly, Manning got a bit of publicity and support too, but how much of this attention got paid to Hammond, Hale or Brown?
3a) I suppose there's an argument that Assange's case should be of more interest to UK audiences because of the UK state's role in the case, but it still seems disproportionate to me - there are
lots of other people who've been locked up by the British state who don't get that much of a fuss made about them. Does anyone even know what happened with Dr Issam Hijjawi Bassalat in the end?
3b) I suppose there's a case for supporting Assange (although not really for prioritising Assange over, say, Hale) if you're someone who makes freedom of information central to your politics, but we all know those people are a bit silly, right? I'm not convinced that it's got harder for the US military to do bad stuff since wikileaks happened, any more than it's got harder for rich people to do shady rich people stuff since the Panama Papers, or the widespread knowledge that climate change is causing the collapse of the conditions that make life as we know it possible has got us to stop extracting fossil fuels.