I don't see any need to invent anything beyond what's in the public domain:
Snowden reckons as Hong Kong as the most developed/politically-stable/safe place to be when the shitstorm blows up, from which extradition will be the least likely. Seems like a reasonable guess. If he'd been working with Russia, it'd be easier to go to Russia - they've extracted agents from the US before.
Say what you want about Russia (economy/industry/military) but they have a large, competent spy agency in the FSB. As soon as this blows up, they are certain to try and get some of their agents as close to Snowden as they can, just in case. I mean, they aren't going to sit back and watch CNN with an asset this big: they don't know what he has, but it's clear he's valuable given the noise the US is making.
Things unfold and it becomes clear China are not as resilient to US pressure as Snowden hoped, and he needs an exit. Cue FSB/SVR offering him a way out. They aren't going to announce themselves as "Hi! We're spys" but as diplomats, the time-honored cover for spying. But unless Snowdenn is naive (he's not) he would have been pretty clear that a spy agency was behind it: it's what they are for.
Now the FSB/SVR really want to rub it in to the US and there's few enough success stories they can bring to the Russian public these days. Spying tends to be secret. So spin the story this way. It's pretty close to the truth, except you make Snowden sound a dumber than he is. What do they care?