One reason I think they would keep HHN at USF is that they can close USF for HHN and still keep IOA and VB open for guest in that area while park 3 ( or 4 if VB counts as one) can be open for the guest in that area as well as any folks in the original area that just head over there due to USF closing early...if they only have one park out that way plus hotels, it might not make sense to close at 5 PM.