I will start by saying that I don't support a trial in absentia of Edward Snowden. But I would like that a president also pardon someone who is found guilty. Edward Snowden is as far as I am aware innocent of any crime in the USA per the US constitution. He is a suspect, he may have even publicly admitted guilt or involvement in something that might be a crime. However he has not been brought to trial in person or not in person and been found guilty of a crime. The president doesn't have to pardon Mr. Snowden. Ms. Loretta Lynch the current standing US Attorney General could just submit some kind of legally binding communication that the US would drop any current and not press future charges of Mr. Snowden if he were to return to the USA. Furthermore that the US would not seek revenge for documents Mr. Snowden may have leaked.
I am not suggesting that I agree or disagree with this view. But I would strongly prefer that our law process is followed and not circumvented for convenience. A pardon seems to strong a process and to soon given the current circumstance.