Martial law doesn't typically push the gov out. As for the new Homeland and FEMA powers, I'm totally in the dark and know absolutely nothing about them. Thanks for pointing that out. It totally escaped me.
I think you mean 'push the local governments out' but it really does mean that. If they have a role to play under a presidential declaration of Martial Law, it is a role given to them in the 'situation zone' -- not a role by right.