No HotSpring spa has ever been made which did NOT have a ground wire built into the power cord. Even the older models which have a plug and outlet for the circ pump have a ground wire built into that cord.
The ground wire is an extra safety device, but not a must have item. Most circ pumps last about 5 to 7 years - you will be replacing it by then. At that time, you can reconnect with the ground if you like.
HTH