After giving pointers, Leo dismissed everyone yet still ended up meeting them again in the kitchen. All of them were having breakfast there, and since Mia was the only one who couldn't fight among them, she was responsible for preparing breakfast and future meals. Leo decided to postpone dragging her outside to kill her first zombie because they still needed someone to deal with such stuff as cooking.
Furthermore, they already had enough people who were capable of killing zombies. Also, if they joined hands with survivors in the supermarket, their numbers would be enough to form a small club according to the rules of their university, which required to have twenty potential club members before forming a club.