I have just completed poll worker training for my state. This issue was not mentioned. But my state, Arkansas, does not have an open carry law. So open carry might be considered suspicious. If someone came in wearing openly and did not have a badge I would call the Sheriff pronto but would not challenge the individual.
BTW, why is it that only "former Marines" are so identified in news accounts?
Never do you see "former Airman" or "former Seaman" or "former Soldier". Just Marines.