That sounds far fetched, because to work for a US security company on any DOD contract you need to obtain a minimum of "L" security clearance which you cannot obtain as a foreign national. I should know, I have worked extensively with the US on deployment to Germany with the British Army as a reservist and we had contractors living with us on base who were all American.
Same with the likes of big ticket companies like AKE, NG, TrippleC, Dyncorps, AEGIS all require "Q" level clearance as you are often working on base and with direct access to classified information. I can NEVER see a scenario that the US would authorise security clearance for a former officer of the Pakistani intelligence service - not in a million years.