according to the online menus, you get a few more items in the skillet at dinner rather than lunch.
I would also think that since the location is a bit out of the way, more people tend to book dinners rather than lunch. Go there after their park day concludes rather than the travel time and inconvenience of trying to make it over in the middle of a day. They probably make lunch a few dollars cheaper hoping to persuade people to come to lunch and lower dinner crowds a bit.