Well, he knows she's known Grace Field, they talked about her being Premium meat. And Bayon would have probably told them if he bought her. On whether or not he should assume the trip there wasn't easy... I feel he's not stupid. But yeah, I do think he will underestimate her at some point. But my more likely guess for what will end him is ??? and... er... wow, I forgot his name. Ray. Them showing up and saving Emma / the others. Not that I wish this would happen but an unexpected bonus on the kids' side seems like the most promising to me.