When those NPCs came close to the place, David had already killed all the Monsters. He is not worried about any loot, as you know those loots will automatically go inside his inventory.
After that, he left that place as he wanted to search for new monsters. David is not trying to go that far away from that place. He wanted to stay close to that place as he would be able to immediately go back to that place.
David is really waiting for Saint Markus to take action. If possible, he would also try to go inside that place once again to find out the truth about that place.
Like this, David keeps hunting monsters inside the game, while in real life a serious meeting is going on inside the Warrior Association.
Saint John, Saint Charlie, and everyone had already come to the headquarters. Saint Markus finally told everyone what actually happened inside the danger zone.