It could be more nuanced than that. In zombie-like states it looks like System 1 takes over and you just do basic activities without really being present in them. In the "flow" state you need to actively engage System 2, although at the same time you tend to reduce the amount of external stimuli to focus on the action at hand.
I think it's different in that in a state of flow, you are intensely focused on whatever it is you're doing, and are able to maintain that focus without struggle.
In a "zombie" state, you may not really be focusing on anything at all, least of all what you're doing.
