If this were back home, I would probably say it was a con to get people to order more. But then again, I can't think of anyone who would pay for food that they ordered because the establishment poisoned them in the first place.

[So maybe it is for sport. Or maybe they have some kind of deal with Matthias, in that anyone who may die gets recruited into his undead army or whatever.]

But I can't disagree with them being fickle, either.