I have some friends that are strongly pro-Manning. Most view Manning was some kinda of anti-system icon, or LGBT icon.
The reality of the situation is that Manning had significant mental issues, should not have held a clearance and should not have been in the military. This was wildly recognized in boot camp, but at that time, they wanted any body that could hear thunder or see lightning. Manning indiscriminately leaked information intentionally to hurt the US military and our diplomacy. Some people have claimed this was to 'expose war crimes', though I'm not aware of any war crimes actually being exposed. None of that seems to matter. Manning supposed to be some heroic icon.
Harvard wants to show off their virtue by nominating the icon rather than the person, I'm guessing.
Snowden, who WAS actually a good guy trying to expose crimes committed by the US government, gets less recognition. The lack of pardon is understandable because he did not get sentenced in court and fled the country. Snowden's position that he would not receive a fair trial is also very likely.
This is just another chapter of "Examples of How Humanity Sucks". And yes, Ben. As Snowden is not being named Harvard fellow and Manning is, it's specifically because Manning is trans and Harvard wants to make a social statement. I could care less what Manning identifies as, but a significant amount of people want the icon rather than the actual person. Manning is profiting off it, and likely will continue to do so.