Your statement at the end basically says, we have classified sources saying Snowden was a Russian/Chinese spy, and we have "feel-gooders" like Oliver Stone saying otherwise, so who do we trust?
The submitted article is by a reporter more neutral and level-headed than either Epstein or Stone, and he basically concludes: there is nothing at present but wild conjecture supporting the "Snowden was a spy" theory. So I think that may be the answer to your implicit question.
Of course they say that. They have to. They're the ones that authorized (if not authorized, they very well knew about it) all the shit the NSA does. Yet to my knowledge there's no evidence for it. One cannot consciously call themselves American while also calling Snowden a traitor (Scotsman fallacy be damned). The egregious misdeeds he revealed far outweigh any laws he himself broke.
The problem with this is you are taking the word of people who:
A) Genuinely and honestly believe that their domestic surveillance apparatus is legitimate.
B) The bias from A has resulted in a true lack of introspection on any real level that what they are doing with A might be viewed as "wrong" by an American citizen.
Once you realize that and realize almost everyone who is used to support that narrative is from the same pool of pro-Domestic-Surveillance folks, it isn't hard to realize their beliefs are likely an outcome of their biases rather than an observation of objective fact.
The truth is we are not going to know until/unless the FSB ever declassifies their debriefing attempt(s) in regards to Edward Snowden. If the intelligence community truly possessed a smoking gun in regards to Edward Snowden, even if it compromised a valuable source or sources, it would be worth using it to terminate the political threat and scrutiny of their operations. The fact they have not means nothing they have on Snowden is conclusive. In other words, no one in the US (or its allies) really knows if Snowden is a foreign agent (or not).
Ultimately, at this point, the fallout appears to be effectively 0 and there will be an expansion of domestic surveillance powers whenever something 'bad' happens. Regardless of the legitimacy of the tool, the fact they are unable to protect it appropriately means its as dangerous to them as it is to us and they are simply too naive to realize it.
Even though I am sympathetic to Showden for his disclosures of gov't surveillance of American citizens and others, the scope, complexity, and execution of operation leaves many questions unanswered.
National security officials (both Republicans and Dems) are quoted in the piece that they believe that Showden operation was an espionage heist.
From the article:
"On June 10, 2013, Sen. Dianne Feinstein (D., Calif.), the head of the Senate Intelligence Committee, described Mr. Snowden’s theft of documents as “an act of treason.” A former member of President Obama’s cabinet went even further, suggesting to me off the record in March this year that there are only three possible explanations for the Snowden heist: 1) It was a Russian espionage operation; 2) It was a Chinese espionage operation, or 3) It was a joint Sino-Russian operation."
So on one hand we have people like the head of the Senate Intelligence Committee and Obama officials who were neck deep in intelligence work, and on the other we have feel-gooders like Oliver Stone, who really don't know what's going on, and who might never ever find out what really happened, because it could be classified for ages...