Just because there's only one email doesn't mean there were not substantial efforts made in other ways. Phones exist. Talking to people in person is a thing.
If you're going to leak 1.5 million documents and flee to China on the grounds of being a whistleblower after following proper channels, wouldn't you want to display some, any sort of proof that you indeed did attempt to follow the proper channels?
People claim this dude was a genius, make him out as some sort of tech/hacker savant, so why not make the slightest effort to show the world you really are a whistleblower?
We also have statements from Snowden suggesting that the reason he took the job was to gain access to those documents and them disseminate them to various world governments, which is a goal that would be impeded by whistleblowing through channels.
