Thoughtful people brave enough to blow whistles seem to be the greatest check on what looks like a secret, unaccountable, illegal centralization of power based on lies from the top of the government on down.
Many powerful people will see him otherwise. I shudder to think of what will become of him, though I'm sure we'll see it played out in headlines.
Whistle-blowers are not our only defense, however, as we all have power too, for example contributing to the Electronic Frontier Foundation (EFF):
"His allegiance to internet freedom is reflected in the stickers on his laptop: "I support Online Rights: Electronic Frontier Foundation," reads one. Another hails the online organisation offering anonymity, the Tor Project."
My personal favorite is the Freedombox project: https://www.freedomboxfoundation.org/learn
EFF: https://www.eff.org
(By the way, I don't know about anybody else, but for the first time I can think of, I'm seriously concerned about the consequences of posting support for somebody like this online. I don't know how things will play out years down the road and who will do what with this information.)
EDIT: Followed up by posting the above on my blog -- http://joshuaspodek.com -- based on comments below.