Strictly speaking, the Disney flight restrictions are "within 3NM _AND_ below 3000AGL". I'm not sure what "3NM or below 3000AGL" would mean.

This sort of flight restriction is kinda silly. It doesn't really increase actual safety on the ground. Small aircraft are really pretty harmless, and anyone willing to try and do real harm isn't gonna worry about this sort of restriction. I suppose it might make some people "feel" safe, but obviously not in this case.