It's a dilemma, he broke the law to expose what he believed was an unethical, overly excessive, and later ruled illegal [1] surveillance program.

In pardoning him would more people feel motivated to become whistleblowers, possibly with different outcomes? How dangerous would that be?

If he's not pardoned, what message does it pass to future generations?

[1] "U.S. court: Mass surveillance program exposed by Snowden was illegal". Reuters. Retrieved September 2, 2020. https://www.reuters.com/article/us-usa-nsa-spying/us-court-m...