I never heard that one. How can that be? I studied journalism law (including photography), and to the best of my knowledge, taking pictures is such place is considered public. If you have any professional knowledge of what you said, I would be interested in how WDW would be considered "not public". I always like to learn something. Thanks for your information.
People are mixing two different legal issues here.
1) Is WDW a private facility, and as such can they legally prohibit photography on their property?
2) Do you have a legal right to take a person's picture at WDW?
The answer to #1 is "Yes, you bet they can." Legally, WDW is private property and they can legally ask you to leave for any reason they wish. This could include failure to observe requested prohibitions against photography. Is it likely? No, but can they do it... sure! Just like you can be asked to leave for other "legal" behaviors as continual line-cutting.
Want a local example of this? Go to your local mall with your camera and want around taking pictures. Odds are after a while mall security will ask what you're doing and ask you to stop. If you refuse, you'll likely be declared a "trespasser" and removed from the property. I know of photographers that this has happened to. Even though you can legally take pictures of shoppers out in "public" at the mall... the owner of the property can have you removed for doing so.
Number 2 is a little trickier. There are a number of factors to consider... but the biggest one is "What are you going to do with the photo?" If it's for private non-commercial use, then it's safe to say that you're free to snap away without fear of being sued by your subject. The courts would recognize that you lose some of your right to privacy when you visit a "public" place such as Disney. But... excercising this right could cause you to be ejected from WDW if you violate their wishes on the matter.
However, if you intend to use it for commerical use, then it's a different story. First off, you'd need Disney's permission to use photos taken on their property or use images of things they consider "proprietory" such as Cindy's castle or Mickey Mouse. Secondly, you'd need a model release from the subjects in the photo. The only exception to needing a model release would be in the case of when someone is just a "face in the crowd."
In the case of celebs, the courts have held that such persons do not quite have the same right to privacy as John Q Public. Sure you still cannot commercially exploit their image without permission or trespass to take their picture, but some things are fair game with them that wouldn't be for you or me. Case in point was several years ago when an "adult" magazine published a "parody" (marked as such in the magazine) of Jerry Falwell and accused him, amoung other things, of having "improper relations" with his mother. Falwell sued and lost because the courts held that his fame made him fair game for parody.