It's kind of funny those enemies thought, for a single second, a person who defeated the demon king in a fantasy world would be beaten by their pesky, provincial tricks. They would have had better luck stealing the largest bomb from the JSDF's arsenal and triggering it to explode near Saitou, at a peaceful moment when he's not expecting anything bad to happen. It still might not do anything, though. They might need to steal a nuke from the American arsenal. It would cause a little bit of collateral damage, but I doubt they'd care.