Hmmmm?
Since Von and Sylvie had already experienced facing the threats of the apocalypse, Xin Feng didn't dwell on them, and chose Brandon, the kid, and Jessica to get more experience from the dangerous world. Although Jessica had seen the demonic creatures before, she still only tagged Xin Feng, and was still inexperienced in actual combat.
Jonathan seemed to be capable of handling the situation too well, so there was no reason for him to tag along.
If it was put into terms of levels similar to video games, Jonathan would be a veteran, and Von and Sylvie beginners. Brandon and Jessica were most likely the person who had only installed the game.