The US government (USG) cannot contain Edward Snowden. As it turn out, he has even more details and information on methods used by the USG to intentionally spy on all Americans, without any probable cause.
I was reading today that the USG should fear if something bad happened to Snowden.To a certain extent, I think the USG could care less about any additional information that Snowden -or his acolites- could release if Snowden were to be covertly (how else?) assassinated by USG agents.
CIA and NSA have already drafted and operationalized strategies to contain whatever damage Snowden could cause the USG. For this reason, I think Snowden should certainly allow his agents to divulge as many secrets as possible and as quickly as possible.
The additional, Snowden guided, releases of secrets in a quick fashion would render some of the CIA's (or NSA's) defensive strategies useless as they would need to step in quickly and this will create opportunities for errors that might help Snowden's interests (to be able to freely get to his asylum destination).
Besides, releasing additional NSA secrets would embolden wealthy Snowden supporters to provide additional help to Snowden. Ultimately, they could pay for a private charter to extract Snowden from Russia and land him safely somewhere in South America. The bad part for Snowden is that even if gets to South America safely he will continue to have a life on the run.