Fair or Unfair They Still Lock Him Away
This was thoroughly covered in a talk at the most recent HOPE. Under the US law as it stands, there is no way out of a conviction. Releasing the information is a criminal offence with NO extenuating circumstances. There is no 'Public Good' defence. Even if Snowden could prove beyond doubt that what he did averted WWII, the court is required to disregard such considerations when determining guilt.
Add to this the current climate dof going after the whistleblower to divert attention from what was revealed (cf that nice Mr Abbott's daughter and her 'suspicious' college grant), they'd lock him away for life in a closed court and the court record would show that he offered no defence.
Truth in politics? We've heard of it.