You can overload cult with whatever psychosemantic meanings you wish, but let's compare the NSA's behavior with a checklist of cult behavior:
[X] The group displays excessively zealous and unquestioning commitment to its leader and (whether he is alive or dead) regards his belief system, ideology, and practices as the Truth, as law.
- "Keeping the US safe" über alles, even the law and the wishes of society.
[X] Questioning, doubt, and dissent are discouraged or even punished.
- Directly corroborated by Snowden
[X] The group has a polarized us-versus-them mentality, which may cause conflict with the wider society.
- Snowden again, and to a lesser extent, the leaked newsletter from earlier.
[X] The leader is not accountable to any authorities
- NSA lied before congress. Zero accountability. Also the "loveint" thing.
[X] The group teaches or implies that its supposedly exalted ends justify whatever means it deems necessary.
- See: Every time an NSA spokesperson makes a statement
[X] The group is elitist, claiming a special, exalted status for itself, its leader(s) and members.
- See: Recruiting ads, the newsletter, etc.
List from [1], and not including things I either couldn't substantiate or didn't think fit.
[1]: http://www.csj.org/infoserv_cult101/checklis.htm