I don't think the demand would be any higher for several items in separate restaurants than it would be for the same items in a single restaurant.
So I doubt the intent was to limit the calculation to a single restaurant, when multiple restaurants are supplied by the same feeder, even though you could interpret the text that way.
If we say this only applies to a single restaurant, I think its going to be very difficult to draw the line between what is a single restaurant, and what are multiple restaurants. For example, I don't see how a food court is really any different than a cafeteria that has multiple food stations. And what about a food court with different restaurants where everyone pays at the same cash register. Is that a single restaurant, or multiple restaurants?
I say if its all fed from a single feeder, I'd either call it a single restaurant, or I'd say 220.40 allows it to be treated as a single restaurant. But I'd also see if the AHJ concurs before going too far down the road.