Tell that to employees at Lockheed, Boeing, Honeywell, Booz Allen... the list of private enterprises or people engaged in government work requiring clearance is large and varied.

They're part of that ecosystem as well. In my experience they're all miserable places to work though, LM in particular.

Have you never hired an ex-Apple employee?

Apple employees/people from other NDA obsessed firms have nothing on the cleared workers. Yea they can be cagey but their products eventually ship and they can talk about them. When you're in defense, once your project ships it stays on orbit for a decade or two.