Do you mean for storing it in the resort or shipping it via Magical Express?
I could understand that rule although I have never seen it.
I witnessed once a guest complaining at the Beach Club because someone's bottle of red wine had busted in a suitcase, and it got all over their suitcase and some others apparently.
The cruise line does say that you must carry any beverage containers aboard with you, and anything they deem "fragile" that you leave in checked luggage could be confiscated. And yes, all checked luggage is scanned before it is brought aboard the ships. But I certainly never heard that regarding the Disney resorts. You do have to realize that the luggage is not treated gently...it's stacked up in the trucks, and thrown around sometimes.