Edward Snowden isnt thriving. The dude literally has to take apart his phone, he has to constantly worry about his specific location being found out even while in russia.

But also the CIA isnt an omnipotent force. During the cold war when the CIA was focusing heavy on the USSR, several dozen undercover agents were killed in the line of duty. The cia doesnt have fully autonomy in other unfriendly countries. England on the other hand is a different story. In fact the globohomos over there probably salivate and glee if the CIA ever asks to violate someones freedom.