My guess is that this whole scammer angle is an act. When he appeared at the end of the last chapter, he seemed a hell of a lot more dour and serious, and you still get flashes of that in this chapter.
Why would he purposefully act like a goofball ? Not sure. Maybe as a ritualistic thing, as in he can't just up and give the protective stones, he has to pretend it's an outrageous transaction or something like that.