Or a secret recruiting method to weed-out those who wont pull whatever narrative is rq'd around said *'needs of the department head'*?
Recruiting is never secret and DARPA, DoD, and the IC are just like the rest of the tech industry and _always_ looking for scarce talent (except they have to pay less than commercial sector thanks to congressional laws).
You seem to have convinced yourself of only negative interpretations as being options, but there really is a lot of overtly beneficial research done by DARPA and a lot of people who really believe in the good they do involved. Not to say that there isn't also occasional bad actors, bad policy, or mercenary transactions, but those are the exceptions, not the norm.
I appreciate your reality check on this - I dont exclusively focus on negative, but I am sensitive to efforts which ultimately result in negative (sociallogically - such as deeper surveillance) outcomes, and while darpa does awesome science, and great leaps in tech - every one of these steps /tend/ to feed surveillance-state paradigms.