I think that Putin simply cares about appearing cooperative with his American "friends", so as to avoid any repercussions. Also there is definitely some play on words here, since we know that Snowden cannot have any control about the information he has already given to various individuals. So yes, he probably won't release any more info personally.
He _is_ cooperative. Inside, he claims we're under an attack of US spies or US propaganda, etc. But when it's time to act abroad, he is too weak to make anything substantial that would annoy the neocon US President.
Just as Italy replied to Snowden that he should have brought the request personally, our ministry of immigration finds excuses like "the procedure takes time..."
For Putin harboring an "active" foreign dissident would make it just a little bit harder to make live less awesome for the internal dissidents. On the other side, giving protection from "evil" Americans to a young naive guy who is being too harshly pursued by the whole overwhelming force of the said Americans' government for possibly violating some obscure laws in order to defend and promote democracy and openness, etc.. - well, Putin looks almost like a good Samaritan (God forbid that Samaritan come to your help like he came for Snowden) and, by proxy, a democracy defender and promoter :)
But imagine he violates the requiements and releases more information. Would that actually be a problem for him?
Putin already said that he won't send him to a country where he may be sentenced to death. So even in that case, he probably won't be sent to the US but to some other country than grants asylum to him.
I can't imagine why he would do something like that, in the open. After all he needs any friends he can get! But even if he was to break his promise of not releasing any more info, it would make more sense if he did it "under the radar". I think he is quite capable of that. Or maybe, he could do it while the Russians are looking the other way :)
