Why does the intent/purpose of the publisher matter here in any way from a legal prospective? I fear that your opinion of his purpose is forming your opinion of its legality.
2. I don't think Assange is accused specifically of furthering the goals of a foreign adversary. If there was evidence of that then he would presumably have been charged with it somewhere.
What benefits or harms a country is orthogonal to what is factual. Any law that claims a moral high ground in protecting facts from being publicized, is used as a club to suppress speech. That is the moral issue, not some misguided idea that you are beholden to where and when you were born over reality to make statements. When you chase people after the fact (information is already published), you're doubling the moral insult. This isn't he ruin of the US, so it's transparently a petty vendetta.
There are practical problems (like state secrets in larger war games, ie Game Theory), which countries have historically forgone any nuance for the club, in the interest of expediency and simplicity. This isn't so complicated. Everyone understands. This is not a justification for totalitarian behavior, regardless of how dressed up the process is.
Motive is incredibly important from a legal perspective. It's the difference between self-defense and murder. I believe you have the burden of proof suggesting why motive shouldn't be considered from a legal perspective, and I believe you'll have an uphill battle doing so.