The Guardian sourced information about it to Snowden's leaks in 2013. What makes you think it's from a separate leaker, and that it's the same leaker as the "shadow brokers"? All I see is conjecture in those links.
Multiple people who have seen the entire Snowden dump claim that various files leaked by specific sources were not contained within the Snowden dump.
Yes, the idea that the "second source" and TSB are the one and the same is necessarily based on conjecture. Nobody is presenting it as a fact, but as a rather likely option based on analysis of data released by TSB and NSA leaks which cannot be attributed to Snowden.
Both TSB leaks and "second source" leaks originate from the same time period, and the same locations within the NSA. That does not mean that they were leaked by the same person(s), but it is a fairly likely option.
I'm not aware of there being a single lick of evidence to suggest that kookery, but even if he was a Russian agent, he certainly accidentally provided Americans a laudable service.
Curiously, the US Government has never made that allegation. There's significant circumstantial evidence to suggest that the US Government may not believe TSB to be Russian intelligence.
USG had no problem blaming Russian intelligence for many other things that were going on at the same time, but they never tied TSB to that bigger picture.
Given what we know about the likes of Hal Martin, there's little reason to believe that only Russian intelligence could have been behind the shadow brokers leaks. In fact, there were rather suspiciously timed twitter DMs written by Hal Martin within minutes of TSB releasing NSA files.
However Marcy Wheeler does argue rather convincingly that Hal Martin's twitter account may have been hacked by TSB in an effort to frame him.
A curious OSINT detail about Hal Martin is that he was using the email address teamtao999@gmail.com on fling.com while looking for women interested in fetishes and group sex. The email address is a reference to the tailored access operations team within the NSA.
His twitter account (@HAL_999999999) created in 2010, also referenced TAO2 in it's avatar at the time of the TSB leaks. It's unclear for how long that was the case, as it was changed later on and there are no archives. Interestingly, he also used to be fairly active on the infosec twitter between 2011 and early 2016 and is featured in tweet chains with many fairly prominent individuals.
His OPSEC wasn't very good, it's perfectly possible he was compromised by some random person.
Edit #89: Okay, I'll throw in one more detail. Very interestingly, it was allegedly Kaspersky who turned in Hal Martin to the NSA after he tried to approach them over twitter. This might seem like a big deal right now, but at the time it wasn't. Russian cybersecurity companies used to be quite happy to work with their western counterparts and law enforcement shortly after this incident when among others Ruslan Stoyanov from Kaspersky was charged with (and later convicted of) treason for allegedly giving information to an American researcher.
It was deeply embarassing for them either way, not figuring out where the leak originated from is much more embarrassing though.
At the very least blaming Russian intelligence would have tied right in with all the other election related hacking allegations.
Also, I think you may overestimate just how embarrassing this is relatively. USG regularly announces that they got owned, is the NSA getting owned worse than OPR getting owned? Maybe not.
FBI would be the primary agency investigating TSB leaks, so no need for a coordinated messaging campaign.
If the FBI believed that TSB was Russian intelligence, it is perhaps somewhat surprising that it's not mentioned in the Mueller report.
We also still don't know how Hal Martin was related to TSB, the timing of the messages sent from his twitter account to Kaspersky (who apparently reported him to the NSA!) does pretty directly tie him to the TSB.
The FBI would still need to coordinate with the NSA for an investigation and public declaration of findings, neither would be in the interest of the NSA to cooperate for.
And the Mueller report was specifically scoped down to not include anything outside of the 2016 presidential election. I don't know why you keep going back to that.
His life literally depends on Putin's whims - a situation which the USA and EU have forced him into. How could you possibly fault him for not poking the bear that he was forced in a cage with?
Not really, he'd be risking whats left of his life by doing so.
There's also rather little reason for Snowden to bother commenting on the very widely known abuses by Russian government, what could he possibly have to offer on that topic that hasn't already been said?
The existing evidence seems to suggest that Snowden was not actively trying to flee to Russia, but ended up stuck there due to reasons outside of his control.
Well, we know at the very least that he obviously had no control over when his passport was going to be added to the SLTD database.
Also, it's not clear why he would have wanted to stay in Moscow if he had a choice. If he had prior contact with Russian authorities, they presumably wouldn't have made him stay at Sheremetyevo for over a month.
Also it's worth noting that in 2013 Russia had much friendlier relations with the US. This was pre-Crimea. It’s not surprising that it took Russia so long to decide what to do with Snowden. Eventually, they concluded that letting him stay wouldn’t significantly harm their relationship with the US while also gaining goodwill elsewhere.
None of this has to do with his decision to seek protection from the Russian government, which is a formal arrangement with their security services, whether you want to acknowledge it or not.
I don't think you can approach this subject in good faith and arrive at that conclusion.
His options at that point were pretty much limited to prison in the US or seeking protection from the Russian government. If you wouldn't have made the same choice as him in that situation, you can reasonably criticize his choice, you'll just have a hard time convincing anyone that you would've chosen prison in that situation.
There's also no evidence that his arrangement involves any work on behalf of the Russian government.
https://www.schneier.com/blog/archives/2014/07/nsa_targets_p...
https://www.reuters.com/article/opinion/commentary-evidence-...
https://www.theguardian.com/us-news/2014/oct/11/second-leake...
It is possible that the "second source" and the shadow brokers are one and the same.
https://www.electrospaces.net/2017/09/are-shadow-brokers-ide...
https://www.emptywheel.net/2017/09/15/shadow-brokers-and-the...
And here's an interesting tidbit about a possible link between TSB and Guccifer 2.0
https://www.emptywheel.net/2020/11/01/show-me-the-metadata-a...