That would be akin to forcing US Cellular to foot the bill everytime someone calls 911 for some bogus problem. You are essentially paying US Cellular for the privilege of dialing 911 through their system to get emergency service response (although as I understand it, most cell service providers are under some agreement with ES to provide the 911 coverage free of charge, provided you have a phone that will work on their network). I don't anyone here sees any difference between the service SPOT provides and that of any other communications carrier service, even presuming that SPOT's ES provisions are exclusive, which they are not. SPOT is not getting paid to mitigate any liability of use, they are getting paid to provide a communications resource. GEOS offers the liability coverage, at an additional fee, which is akin to Ford making the car and Allstate providing the insurance for the operation of the car. I think that would be an affirmative defense. They are charging money, but not to relieve the end user of their strict liability of responsible use. No different than trying to sue Gun manufacturers for making guns that kill because some knothead used a gun to commit a crime.
As we've already established, abuse/misuse of the SAR services is punishable, regardless of the method used. Allowing an easier method to do it does not imply a liability of use, no more so than would making a gun that is able to shoot more than one bullet between reloads an assumption by the manufacturer of liability for how a gun is used.
It seems there is only one person missing the point in this debate. Is it me?
Those policy disclaimers that GEOS published seem to be a standard type: Exercise due diligence, and you can't fix stupid.
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The ultimate result of shielding men from the effects of folly is to fill the world with fools.
-- Herbert Spencer, English Philosopher (1820-1903)