The reality is even if they pardon him, the guy will never be safe in his home country. Thousands of so called "patriots" believe this man is a traitor. Very sad especially considering what little has changed since the leak.
I wouldn't completely rule out the idea that someone might take a shot at Snowden were he to return, but at the same time I doubt that the vast majority of people who label him a "traitor" feel strongly enough about it to personally try to kill him.
I'm not sure that's quite apples-to-apples, given: (1) US political asymmetries; (2) nobody accused him of conspiring with a clear "The Enemy"; (3) Cheney was already a multimillionaire with private security and moving in rarefied social circles.
If Cheney was once hunted by the US government, widely accused of being a communist spy, and he shopped for groceries like a regular person, I imagine the odds of an attempted attack would increase.
Only crazies and communists and white supremacists have used assassination as a political tool in America in the modern era and that hasn't even happened in forty years.
I expect Snowden would be perfectly safe under a pardon. Until then I'd advise him to avoid long sight lines; America's official enemies have a way of finding themselves exploded at a nice sterile distance.
But the other side is nothing like that.
That would allow Snowden to go mostly anywhere and do as he pleases... instead of being stuck in limbo at an airport or as it currently stands allowed some degree of freedom within Russia. I should point out that pardoning Snowden allows him to LEAVE RUSSIA; which is a thing that I believe anyone should like to allow him to do.