Marjorie is not fond of being accused of cannibalism. She and Mortimer are the two conflicting leaders of the White Gloves and by default becomes the most influential member if, during the quest Beyond the Beef, Mortimer is ousted.
pcxbox360ps3 Although Chauncey tells you to find Marjorie at the restaurant, she may not be able to be found outside of the members' section, making Beyond the Beef impossible to complete without an appropriate White Glove disguise. [verified]
PC fix: Type into the console: prid 0010D4F1, moveto player
Multisystem fix 1: Killing a White Glove Society NPC allows for looting of White Glove Society Attire, White Glove Society Mask, and White Glove Society Members Key (unlocks the Members Only Section); this can easily be achieved with a silenced gun while hiding (for instance, target the idle NPC in the far corner of the restaurant). Equipping the White Glove Society Attire and White Glove Society Mask allows the character to enter the Members Only Section without being killed on site (the White Glove Society Members Key unlocking the door to the area). Inside the Members Only Section Marjorie can be spoken with as normal, after which she is triggered to commence roaming the casino once more (her normal non-bugged state).
Multisystem Fix 2: It is possible to get Marjorie out of the members' section by throwing a grenade while in the members' section under cover of Stealth Boy. If done right, no one becomes hostile and your relationship with the White Glove Society remains unaffected.