I don't really think that because there's a unique water coaster ride makes it a "legit 3rd theme park". Water parks have a much more limited appeal - and to a degree a more limited utilization. (Southerners - folks that can make the drive - still make up the largest portion of Florida theme park visitors, and they won't go near the water when the temperatures drop below 85. This means 4 months of the year this park will be very empty.
Now - it very well could be the best water in Florida - better than Disney's - and that may be the case. The big question will be do they treat it as an equal from a ticketing standpoint. In other words - are regular APs valid there. My suspicion is this will NOT be the case.
100% agree that it won't be a legit 3rd gate.