I'm surprised both "NSA" and "surveillance" are two of the fastest shrinking words. I thought we saw more now than ever. Shows how perception doesn't always match reality.
When the Snowden leaks first dropped, the front page was absolutely overwhelmed with NSA news, to the exclusion of nearly everything else. Would not be possible to keep that level of interest up without making this is an exclusively NSA/surveillance-driven site.
IIRC the mods also soft banned it because of that. So posts with the word "NSA" in the title get penalized and ranked much lower than other posts. Hence the shrinking.