It's private property, if they say you must wear it for the safety of their guest and most importantly employees, you have to or choose not to be on their property. Same as a gun, you can carry it with a concealed weapons license in Florida but you can't on their property. I understand kids with sensory issues i.e. autism and they can make exceptions for them if they choose. Otherwise you skip your visits to WDW for the time being if you like.But it isn't mandated by the state, some counties do but we are also only in phase 1, by phase 3 there more than likely won't be required, just recommended if that across the state.
Each phase/month goes by things will change.