My take on this whole thing is simple.  Send the firefighters.  

 I would like to know just how private this fire department is,any grants,goverment help etc.  If it's truly private and they don't want to go then don't.

 Can't think of one around this area that doesn't have their hand in the public till,so they should go.

  Put the fire out send a bill.  If not paid in three months then put a lien on it. No big deal it's done all the time for other things. Fire dept eventually gets their money. The neighbors that do pay won't pay anymore. Nobody left holding the bag.

   The way I see it unfolding now is the homeowner hires a good lawyer.He digs up the finances and finds money coming from sources other than membership. Maybe some of the tax money of the same homeowner.  Then it gets hot... They will wish they put the fire out.