I guess one question would be despite having a gas pump there, unless they are pumping a 100LL into the boats, they will need the infrastructure (ie: a separate fuel farm) to fuel the aircraft. Unless something has dramatically changed, I believe an aircraft would be very unhappy drinking anything but a 100LL.
Lets not forget, when I park my Turbine Beaver on floats out there, I will need a fuel farm for Jet-A too.