This is unfortunate--in a just world everyone doing this would be imprisoned for many years and have all their ill-gotten gains stripped from them--but a real fact. And the typical NSA software developer is certainly highly qualified and very, very smart. Going purely by business concerns, if you have a need for someone with the skill set that'd come from working for the NSA, you can't afford to pass them up just because they worked with the NSA.
You can also be sure that, even if the NSA were disbanded fully and all its employees hated so much that they could not get domestic employment anywhere, many international actors would be extremely excited to pay top dollar for their talent. And by top dollar, we're not talking piddling six figure salaries.
Now, if they decided they wanted out, well ... good luck with that in the manner you describe. I suspect that it won't be too hard, though. They deal with "Big Data" problems at a scale that few do, so being an NSA engineer likely is bound to be a similarly prestigious resume line as working for Google. Aside from the working for an evil entity part, that is, but some employers will not care as much about that.
Sometimes employers are willing to take that risk.
Do you think Ed Snowden is now more or less employable now?