What are your actual damages?
One month of cell service? Then that’s your compensation.
If you planned so well, what was the back up plan if the phone was thrown overboard by the three year old?
And even if you could suspend belief and pretend their problem was caused by termination of service, it is not foreseeable that would cause them to be stranded in a boat.
Beyond that, they did have an alternate means of communication that they effectively used to call in a rescue.
That lawsuit is a loser, even in Kalifornia.