Let it play out - if they come out of their shells and RP, they'll make it interesting. And if they save the day w/o a fight then you've got something in your library of encounters to pull out some other time when in need.
As for how to run to cookout: Let them figure out party logistics, but be ready to be an NPC or two that jump in with suggestions. Think through the things they'll need (food, drinks, guests) ahead of time and come up with some options if they ask the right questions. Maybe someone knows of a local pig farmer who'll trade some pork for an IOU from he party.
Then think about how Teostra may respond. If they make friends then maybe Teostra reveals that he has been talked into hunting the party because ____. That can set you up for your next adventure. Or two adventures, counting the pig farmer.