One flaw in the GF is that Michael, given his Marine service, would somehow be nervous or afraid when confronting gangsters (i.e., when he is standing outside the hospital when Vito is being set up for assassination, lights the cigarette, and his hands don't shake; and when he kills the Turk and McCluskey in the restaurant).
Your post confuses me somewhat.
You say that one flaw in the GF is that "
Michael would somehow be afraid..."
I did not see, in that scene, any indication of Michael being nervous or afraid. As a amtter of fact we've spoken here on these boards on many occassions that the scene you are talking about may have actually been the defining moment for Michael, the moment that he realized that he "can do this" because as he looks down at his hands as he is lighting the cigarette he notices that he is not shaking. He was cool, calm and collective through that whole ordeal.
So if I may ask, where is the flaw in that scene? Where does it indicate that he is afraid or nervous?
