But it's also really not the sort of thing that you should just allow to happen, if you are running a massive complicated scam on the alien visitor.  Unless you figure that you can't really stop him from casting Owl's Wisdom on himself so you might as well just let it happen?  They could've told him it would only last ten seconds and then sneakily hit him with a Dispel Magic, he knows that's a standard magic, it was in the books.

But it's also not the sort of thing that you should just allow to happen, if you are running a massive complicated scam on the alien visitor.  Unless you figure that you can't really stop him from casting Owl's Wisdom on himself so you might as well just let it happen?  They could've told him it would only last ten seconds and then sneakily hit him with a Dispel Magic, he knows that's a standard magic, it was in the books.