Just because this was an emergency doesn't mean it wasn't unexpected. We would want firefighters to go the next town over if there was a fire there, so it seems like their insurance policy was improperly under specified.
They did have a plan, and they did execute on it - exactly as they advertised.
...and if they decided to risk it, and put out the fire anyway - and tied up all their pumps hoses ladders and trucks, and then another call comes in a few miles away - from someone that did pay for coverage - how much liability would they have for tying up all of their equipment at a fire they are not supposed to be fighting, and thus unable to respond to the fires they are supposed to be responding to?
People in this country should be free to make stupid decisions - and free to suffer the consequences of those stupid decisions.
Universal health care might have changed the firefighters' minds. On the other hand, perhaps other liabilities would not have been covered too, so maybe not.