"Alright," he answers, watching Johnny with worry. He's not sure whether the book is actually dangerous or if it's just Johnny's imagination coupled with some sort of mental health problems, but either way, he doesn't see the point in digging further into it. Johnny had seemed pretty well-adjusted the other times Seth has met him, so perhaps it's just a thing that becomes a problem when the book in question is brought up or present or whatever. For right now it seems more relevant to solve the problem at hand.

"Don't suppose you've got a shredder somewhere? Or a fireplace?" he suggests. There's so much paper around, one might even be hiding around somewhere. If destroying this book will help Johnny somehow, he doesn't see why they shouldn't.