I find it hard to believe there's any sort of recruitment shortage. The NSA does today what it did 5, 10, 15, etc years ago. People interviewing for those positions know exactly what they're getting into then the same way they know what they're getting into today. The whole "OMGZ SPYING ON MY MAY-MAYS" sells on here on reddit, but apparantly lots of people don't take that view and instead see sigint as a legitimate need, like having a standing military with nuclear weapons or intervening into foreign countries. Arguably, good sigint means less conflicts and more wins. Hitler's Germany was damaged greatly by sigint hero Alan Turing. Funny how we celebrate Turing, but a modern Turing today would be vilified instantly. The world, if anything, is much more dangerous today than in the 30s considering how many nations have nuclear weapons. Honestly, if I had the choice I'd rather work there than find new ways to deliver annoying click-bait ads at a place like Facebook or get kids hooked on some milquetoast WoW-clone.
The Chinese, Iranian, and Russian sigint guys aren't taking some moral stand either. They're just getting their assess to work the same way we do.