I did the same. I found the same about it predating Snowden, but I also found this quote from J Alex Halderman in a remembrance of Peter Eckersley.

> That summer, Edward Snowden came forward with chilling revelations about NSA mass surveillance, and the need for ubiquitous encryption became clearer than ever.

It’s not a claim that it was the instigator, but it seems like it was heavily on their minds.