Well, there's our answer. I saw the National Guard on-scene commander describing the situation on Sunday night, so I knew they'd had them at some point... appears they had them throughout. The Superdome "no food" phrase has become one of those articles of faith now, that is just assumed to be true even by a number of posters on this site. It's sort of like that "Bush said the threat was imminent" canard re: Iraq. It's been repeated so many times that it's now accepted as true even though it isn't.
Basically, I think there's considerable confusion between the Dome and the Convention Center. Food and water weren't available at the latter originally because it wasn't planned to be a shelter, and FEMA didn't find out people had gathered there until the media showed up and started showing people complaining. The media, in turn, made the mistake of assuming it was a designated shelter, then basing their stories on that.
There's a lot to be discovered when this is all over, and I suspect that much of the more hyperbolic media reporting will be thoroughly discredited. Not that they'll let any of their audience find out, of course.
At some point, I know that I heard the MRE's and water were being shared with the convention center....instead of 3 times a day, the MRE's at the SD were cut down to twice in order to give some to the convention center....and you are correct. The CS wasn't a planned shelter.
If the incompetent govenorette had allowed the Red Cross in, the people on Sheps overpass would have been fed, also.