I think most of those who condemn the MDR for lunch have never tried the MDR for lunch.
In general, one MDR is open for lunch only during sea days, so while in port is moot.
While open seating, you can state you want a table or one, or two, or whatever. All members should be present.
some lunch menus can be found here:
Carnival Spirit Menus - April 11 - April 22, 2010, B, L