True, but I've been following the same general principle. That if all characters die from a bite spreading, then the bandits leave just as if it was overrun. Because essentially, that is what a bite spreading would represent - the players becoming zombies and basically overrunning the location.
If a player kills their survivor to stop the spread, and it is the last survivor at a location with bandits, the bandits stay because the threat is gone.
I disagree with this. Bite spreads among player survivors because they are allies and close together.
Bandits are not. They are a separate group entirely. They are not called 'survivors' nor do they have influence rating.
Thus bandits stay around. I'm pretty sure that's the intent of the designer as well.