Blake should NOT be military; he should be a dissident, yes, but not military. He should be an academic, a bureaucrat-- a privileged uninvolved man, so his involvement with the rebels will be more of dramatic step. When he witnesses the massacre, it makes him a true believer.
So we do away with his history of political agitation that saw him "brainwashed" and his family murdered before his re-awaken and exile of Cygnus Alpha?
I wander - would Blake have been such a menace to the Federation if he didn't have the history?
As to his civillian role, apart from Vila's comment that Blake was an Alpha grade on Earth I don't recall anything else being said definitely about his background so he could be bureaucrat