I never thought that Breen was thinking of mankind. Perhaps at first, yes. When he surrendered the Earth he was clrealy thinking of humanity, but overall it was for himself, and it still is. He really doesn't care, his lines reflect this and with him so willing to get off of the Citadel, its clear he just wants to endulge himself in another world and race, bugger humanity.
I think its obvious that Breens been twisted and manipulated by the Combine advisor, its what it does, and its been preying on Breen, turning him over the years. Breens out for himself.
