Peggy decided to go with the offworlders on this trip as a demonstration of Panem's support and to encourage unity in D13 (since she doesn't like the idea of just making them feel like outsiders within the rebellion), so she'll be around to pick up kids. She knows what they're going through, so you can expect a very understanding woman who is ready to deal with it if kids end up mistaking her for a threat and attack her. Who wants to be saved?

Also, she's there to mingle with other rescuers or people she can meet in the arena, so there you are. Come have fun with her.