I'm not saying it is easy and flawless, just that calling it "extraordinary" is in all likelihood an exaggeration. They do not need to know where exactly he is at every single moment to make travel too risky for him. Them not knowing where he was during that incident does not imply them not knowing where he is now. Neither it implies them not having an informer who would tip them if the Snowden tries to arrange secret fly.

CIA had a lot of time between them and now. It also have a lot of resources and his movements are likely to be top priority for them. Them knowing he boarded a plane is real risk for him.