To be fair, Snowden wasn't endorsing Zcash based on his own cryptographic or security expertise, he was responding in agreement to a tweet regarding the cryptographic background of the Zcash developers with a general statement that privacy is important with regard to cryptocurrencies[0].

The primary reason anyone cares what Snowden thinks is his celebrity - it should be a non-story, although the Twitter thread is an interesting read.

[0]https://twitter.com/Snowden/status/913544739542241282