I ran into this today. Flying Delta, boarding pass shows DL Diamond and first class.

I wanted to enter the central security point just because wanted to have food at Ivar's before going to the south gates for my flight. I was turned away and sent to the south checkpoint.

Kinda dumb in my opinion... just had to trudge to the south checkpoint, go through, then go all the way back up to the central area to eat.

Is this really the policy?