Machiavelli warned against relying entirely upon mercenaries. Blackwater should be for support, nothing more.
I will take my chances with Blackwater over liberals who cheer muslim agents at Langley and fail to search bombers in a war zone. Blackwater kept us safe for about 8 years. The CIA employees cheer muslim agents at Langley.
A mercenary is someone who for the right price will fight for any country, without regard to his own country's interests, even against his own country's interests if the money is good, because they are loyal to no one but themselves.
That certainly does not describe the individuals who work for Blackwater, whatever name it goes by. Do they get paid? Certainly. But so do all our military personnel, and we don't refer to them as mercenaries. Just because they work for a firm as specialized as Blackwater does not imply a willingness to work against the interests of their fellow citizens or against US interests. The employees are military personnel who have sworn an oath to defend the constitution when they signed up for the military, and they don't forget it just because they retire after putting in their twenty and go private. The area where they differ from military personnel is that contractors suffer no fools- the military must endure every idiot the politicians put in charge, for as long as the politicians want to keep them in command.