When operating under SAD or Title 32 they are only restricted by state law. A Governor can activate and direct the forces to use force if necessary, to enforce law, etc if the states laws allow it. Posse Comitatus as you listed does not apply and if State law allows it they can most certainly be armed.
Thanks! I was thinking they could be armed (if OK under state law), but there seemed to be conflicting thoughts to that up thread.