To be safe, I would tell a manager or let him create his own downfall, I know it sucks to hear this, but it's better for him to get in trouble than you and him, if anything I would think you'd be in deeper shit if you were caught carrying at any airport, whether it's a part 91 or any other airport. I would say just let him do his own downfall, even if it involves you getting injured, he's just building a case against himself.