I'm not sure if Snowden particularly knows what he's talking about in this case really. I mean, the 51% attack is hardly something most don't know about.

http://cointelegraph.com/news/115133/edward-snowden-on-bitcoin-bitcoin-by-itself-is-flawed

“Obviously, Bitcoin by itself is flawed. The protocol has a lot of weaknesses and transaction sides and a lot of weaknesses that structurally make it vulnerable to people who are trying to own 50 percent of the network and so on and so forth.”

'Despite his concern for the digital currency, Snowden believes the concept of tokenization and proof of work could be implemented to create “some very interesting things,” which “people can basically pay for access other than direct transfers of currency that originated with an association to their true name.”

Bitcoin's associations to name/identity is due to the square-peg-round-hole problem of many developed countries now placing their structures/legislation onto Bitcoin and the purchase trading of it, not any inherent flaw in Bitcoin itself.

If people will give identity to these exchanges/circle etc. to play with the ball, then what does anyone expect? Kind of disappointed with Snowden now really. I mean anyone can throw a sound bite out there like: “some very interesting things,”

What does that even mean? It's like me saying in the dawning age of home computers that they'll be able to do some 'very interesting things' one day. Anyone could have said it. I expected more from Snowden to be honest.