Why sympathize with them? They either decided in bad faith that working on an interesting problem was more important to them than acting ethically, or they are saying "I'm just doing my job" also in bad faith. These philosophical decisions are simply malicious relative to the rest of us.

There is also the possibility that they have been deluded by nationalism or propaganda in order to believe that a panopticon is acceptable in a democracy, but there isn't much we can do to help these people connect the dots between the panopticon they are helping to build and Orwellian thoughtcrime-- we simply don't have access to them that we could use to be persuasive, as you mentioned. I think this population of people is actually pretty large among the government contractors.

Finally, though you are correct that NSA employees would probably mention this, for the purposes of agencies operating in the public interest in a democracy, the concept of "insider knowledge" is not permissible. I say this not to suggest that we make all the operations of our clandestine groups transparent, but rather to suggest that the complete ignorance the American public has found itself to be in is a byproduct of intentional grooming along the lines of "national security secrets" which really are intentionally crafted backdoors to the process of informed democracy. The citizens not involved in agency day-to-day have a firm need to know the methods and rationales used, and they need to have direct and powerful oversight.

We don't have any of these things, currently.