Is it unreasonable to expect such a thing? Suppose Snowden beats the odds and makes it to Ecuador. Would you be surprised to hear that he was found dead in his apartment in a year or two? Would you be shocked to learn that the US government was involved?
Why should we trust the US government to follow the laws of Ecuador, Venezuela, or Cuba? Snowden runs a real risk of being covertly kidnapped without regard to the laws of whatever country he happens to be in. He runs a real risk of being killed by a drone strike. The US government has done all of the above in the recent past, to both citizens and foreigners, in various regions and countries.