Obama does not care about Snowen. By this time, Obama has probably bought the *IA's line that Snowden is the anti-christ, that should be shot on sight. Under normal circumstances, he would just say that he will not pardon Snowden because Snowden is bad.
Also, Obama has competent legal help, as well as being a lawyer himself. He knows he can pardon Snowden if he wants to. But the situation visa-vie Snowden allows Obama to state a principle that disallows a pardon for Hilary, without referring to Hilary or even admitting that he knows it might apply to Hilary.
This is a very elegant way to throw Hilary under the bus, without even mentioning she might exist. He can say to Hilary supporters when the question inevitably comes up "I must apply my principles without fear of favor."
Whatever you think about Obama you have to admit that he is a very smart fellow.