I didn't say anything was "wrong" with that. What I said was it didn't make sense to me.
It doesn't make sense to me because it is a park that regularly closes at 5:00 or 6:00pm. It is a park that, currently, is open after dark very rarely. It is a park built around attractions - the safari, the conservation station, Discovery Island Trails, Maharajah, Pangani, the Oasis, Flights of Wonder - and atmosphere and entertainment experiences that are currently not enjoyable after dark. (I know there is a night safari coming.)
Keeping a park open four or five extra hours, with only a handful of things to do, makes no sense to me. Paying all those extra operating costs in the hopes of trapping people there to shop/eat doesn't seem like a workable idea. I believe most people will either leave and come back just for the show, or not be willing to stay at all. So you'll be running a ghost town from dusk until 11:00.
The opening of Avatarland would certainly help with this. People may be more willing to stay, or hop in late, if there are more then five or six things to do. Maybe.