1. If the interests of the public and US adversaries coincide, then there may not be a distinction. For example, if the US government had gone rogue and was spying on literally everyone (as, indeed, appears to have happened) then it is useful to both the public at large and the US's adversaries to know about it. It is good journalism to report on it. Ditto war crimes and all sorts of other shenanigans that Wikileaks has uncovered.

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.