For years we’ve all been reading how museums, like airports and ballparks and other culinary-hostage situations, have been trying to upgrade their food offerings to reflect the great advances toward something approximating American cuisine. So it was beyond surprising for my consort to try to walk into the Met on Saturday with our market bag bulging with tuna belly and broccoflower and Illy espresso from Chelsea Market, along with a doggie bag from lunch at the New French. The security guard refused to let him pass. Absolutely no food is allowed inside, he insisted. The bag could not even be checked in the coatroom. Bob headed home dejectedly while I stayed to meet a friend as planned. But it sorta makes you think you would never want to eat there. What the hell do they serve if food is forbidden? Dendur dust?