So people can get jollies downvoting me for misremembering something I last read about 4 years ago, if they want. The bigger point is that the depiction of Snowden as simply a "SharePoint administrator" is clearly off base, according to multiple journalistic accounts (which are very easily findable).
I don't think he had more technical capability than a typical SharePoint administrator at the time of his leaks. Setting up a VPN is pretty much sysadmin work. Digital Ocean had excellent guides on setting up OpenVPN and IPSec tunnels on CentOS in 2012.
SharePoint administration is credible tech work, it's just unrelated to programming and crypto.
He has had time to learn about any subject he wants to since. He may very well be a privacy or crypto expert now. If he wants to become an authority on any of that knowledge, he'll need to write about it with justification. Otherwise, why would anyone take him at face value?
Well again there were several journalistic pieces at the time that summarized his work both for the CIA and as a contractor that (taken together) make it pretty clear that, while he's not like some domain expert, his crypto and security skills (before the leak) went significantly beyond that of a typical sysadmin. And again, they're pretty easy to find my keyword searching and the like.
I flubbed the detail about the VPN though -- apparently all he did for Poitras was set her up with a (significantly) enhanced mail drop.
His Dell position in Japan was possibly more broad, I don't know. His Dell position in Hawaii, however, was rote SharePoint and Active Directory administration, according to the articles I've read.
I'm interested in reading a credible article about his skills in cryptography, etc. if you have them on hand.