The "in bed with Russia" thing is just a smear. No one has produced any evidence of this, and it's really hard to make it match up with how everything unfolded.
The biggest clue that what your friend says is wrong that Snowden wouldn't have gone public and announced himself if he was spying for Russia.
"It is difficult to get a man to understand something, when his salary depends on his not understanding it."
I doubt he's fond of Russia, either, and he's made some passive-aggressive jabs at them on his Twitter.
That said, it can't be ruled out that he divulged even more secret information to Russia's intelligence services as a condition for asylum, but I don't think there's any evidence it was one of his motives when leaking.
Do you really believe Snowden was a double-agent, or that he was a conscientious whistle-blower? That's what it comes down to.
I took his opinions with a grain of salt given his background, but also couldn't refute due to being relatively unfamiliar with the Snowden saga.