Denny's and special menus

So I took a nap today and got up at 10:30. Denny's is always open so I
went there and they handed me the special limited after 10 menu.

When I asked for a salad the guy looked at me like I was a retard and
said that it's after 10 so there is no salad.

Why would you have a special late night menu if it weren't calibrated
with what you actually serve anyhow?