Blackmailed by the NSA? That’s probably the reason why Trump don't grant a pardon to Snowden.
Discussion
More like the opposite.
During the Obama administration, Obama wanted to fire Michael Rodgers (NSA Director) because he knew the truth about Eric Holders Fast and Furious operation, Obama's real identity, and other shit.
Rogers was also the FISA court whistleblower and personally went and questioned the judge of her actions and lack of information.
Rogers along with General Flynn was how candidate Trump found out about the Trump Tower wiretapping/bugging.
Once Trump was in office Obama told Trump to avoid General Flynn and not hire him. Trump didn't give a shit and hired him anyway. Later pardoned him as is now an advisor in his current administration.
So did Rodgers (NSA) help candidate Trump or right a wrong of the previous administration?