When the hurricane knocked out New Orleans, some private law abiding citizens who were just trying to get to high ground were attacked by police. Considering the amount of chaos that can prevail after a natural disaster, I would want to be able to protect myself, since the resources that I am using and in control of: Electric power, gasoline, food, water, heat, shelter and radio communication access to the outside for emergency services, reporting of crimes, makes me a TARGET to some people!
If the rules of ARES, functionally disarm me, and something bad happens to me, they have indeed exposed themselves to liability, just as the law recognizes that businesses that post gun control signs in Wisconsin, have created a libility for themselves.