So, Snowden continues to be a badass.
Faced with the unpalatable prospect of being used as a propaganda pawn, but in a situation where it might have been difficult to say no… he doubled down.
Here’s how I read the play. Putin wanted to demonstrate he had a modicum of control over the high-profile whistleblower at a moment where Russia was facing a shitstorm in the West in regards to Ukraine. Therefore, his operatives politely asked Snowden if he wanted to join in the teleconference, whether politely by Western standards or politely by Russian standards of “here camera, you speak!” is unclear.
Snowden on the other hand does not want to be under anyone’s control if he can possibly help it. That is a Teflon-greased slippery slope to a very bad place when any spies are even remotely interested in you.
He’s also nothing if not true to his ethics — a man on a mission in the truest sense of the term, even if the mission appears to be his own. He has a raison d’être and he’s sticking to it.
At the same time snubbing Putin might be a Poor Idea. So, what’s a guy to do?
Give ’em what they want… but leave ’em with enough of a bitter taste they don’t come around again. Call it the “you want my wallet? OK, here’s my wallet. You want more? Someone call an ambulance, we have a severely injured mugger” strategy.
Which is what Snowden did. He went on Russian state TV, explained mass surveillance doesn’t stop terrorists, and made Putin deny that Russia did any. Nothing overt, but… watching the original TV clip… you can see everyone in the audience start to lean for Putin’s reaction as the question is translated.
Not what they were expecting, for sure. And, in a country that values a “no fucks given” approach to power dynamics*, a move that probably won him some grudging respect from the Russian TV audience. After all, here we have a country whose citizens famously distrust their government, yet probably never in their lives did they expect to see the question of government spying on citizens make it to state-run TV.
* (If you’re a factory owner and you don’t pay “protection” to the Euro/US mob, you might have some suspicious accidents, labor unrest, or exasperating local legal trouble. The Russian mob, on the other hand, has been known for firing rocket propelled grenades at factories whose owners didn’t make “suitable arrangements” before beginning business.)
Snowden points out in his response to critics  that his question to Putin was almost identical to Sen. Wyden’s famous question to Clapper, which triggered the Clapper Lie which, in turn, went a long way to pushing Snowden to leak. In other words, the question he chose to ask Putin carried a subtext of inspiring future Russian Snowdens.
As one commentator put it:
“Snowden is (once again) playing a game where he’s several moves ahead of many folks.” 
Indeed, Putin was right when he pointed out both he and Snowden were “former” spies, and called their exchange a “conversation between professionals.”