If I were on the council, there's a pretty obvious reason why I wouldn't have chosen the pizza (and maybe the kids thought of it, too, and CBS just didn't show it to us).
The reason is this: Those kids have been on meager rations, with little meat, for eight days. If they ate that greasy pizza, it would go right through them. Then they'd have 39 kids with diarrhea lining up for 8 outhouses. It would be a disaster.
Switching gears from the pizza issue: I think another thing the council should have done is call Greg in privately and tell him that they know he wants the gold star, and they know he's working hard for it, and his contributions are recognized. Then they should say that he is abusive and antagonistic, and for those reasons, he is not a candidate for the star this time, but IF he keeps up the good work AND makes an effort to get along with the other kids, they'd consider him for next time.