There is no reason to make a deal with Snowden. He has already clearly spilled all the beans he had in his possession. The only reason to bring him back now is for execution. Clearly, we can't make a deal that he would accept that would allow us to do that.
Even if we accept your premise that there isn't a reason to partially pardon Snowden based on the motivation for and result of his actions, the fact is that Chelsea Manning was not executed, and could be released after just 8 years in prison. Why are Snowden's crimes worse?
