My understanding from all reporting - that is the policy. No weapons can be carried around on property.
Last year at least two people were arrested trying to bring guns into Disney World theme parks.
They were charged with Carrying a Concealed Weapon.
Was stated he was banned from Disney properties, not sure on hers but likely.
And until ALL guests walk through those metal detectors, there very likely are guests in the parks with guns.
In regards to the folks you say are walking around with guns; they risk being arrested, being asked to leave resort and receiving a no trespass from Disney which means they can't come back again ever unless Disney agrees to lift it. Probably not a good chance of that given the charges. Is that really worth carrying your gun around? I don't think so.