The confusion of ownership of Wet 'N' Wild probably stems from the fact that NBC Universal jointly owns Universal Orlando with the Blackstone Group. Universal Orlando, according to the Blackstone portfolio, consists of Universal Studios Florida, Islands of Adventure and CityWalk.
Also, the Universal Studios Recreation Group no longer exists and has been replaced by Universal Parks & Resorts which is a division of NBC Universal. If you want more complication, NBC Universal is owned by GE and Vivendi.
If Wet 'N' Wild is owned solely by Universal Parks & Resorts and not under the Universal Orlando division, it could be a dilemma of a business decision to move the waterpark onto Universal Orlando property.
Just a theory, as I could not find ownership of the park listed in either the Universal or Blackstone portfolios.