Don't really understand the implied connection to NSA or GCHQ. My theory as to why Snowden is popping up in some of the tweets is because the bots are probably using something like Markov Chains to generate real sounding (as far as Twitter spam detection is concerned) tweets sourced from trending content.
The accounts would then be sold as followers, which is an attractive service to some for a variety of reasons
The accounts would then be sold as followers, which is an attractive service to some for a variety of reasons