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.