If Treehouse has that rule they don't enforce it....I stayed there and had a fridge and stocked it up with my own drinks & stuff, No Worries!!
I've been staying at the Treehouse for the last 6 years and never had any problems, I would never stay anywhere else on the beach.
The breakfast buffet is great, the beach bar rocks, all the food is good, the beach area is nice and secure thanks to Moses and best of all the staff are all friendly and great people ! The rooms are clean, the grounds are beautiful >>>IMHO you can't go wrong with the Treehouse !!