We did that at the Hilton (I think that’s the same hotel you’re referring to) a few years ago. We used points so the room was free. It was nice to have showers and a place where the kids could flop. The beach is very small and the view not much to speak of (you’re looking directly at the cruise ships) but it was a way to make lemonade of lemons as we did this on a RCL cruise where they gave us a Nassau day instead of the planned trip to their private island. Personally, on Disney, I’d rather stay on the ship, but on our particular RCL cruise, it was an older ship with little to do and that was our only chance to get in a beach day.
Edited to add: I googled the British Colonial and yes, that’s the hotel we did the throwaway night at, but it’s apparently no longer owned by Hilton.