"No, you won't go there, no one shall go there." After hearing the whole story, Duke Wortham came to a simple decision. He can't allow them to go there.
His relationship with Jester still remains a mystery. Knowing the reason why Jester couldn't fulfill his promise before, Wortham knew how much Jester needed this win. He needs to succeed; that's the only possible way for him to learn more about the Dream or nightmare realm.
The world where illusion becomes reality, and thoughts are given forms. It's his only escape and Jester is his gateway to that world. Not to mention, the amount of Nightmare's essence he collected last time had been able to Dirty his essence enough that "those" people kept their distance from him. But it won't be long before he loses that, so he needs not the resource, but the method to access that resource.
