Question
The Baron kills Dr Yeuh, who betrayed Duke Leto's family:
Baron Harkonnen: I said I'd set her free. That you could join her. So, join her.
He then turns his attention to motionless Duke Leto:
Then scene cuts to Paul and his mother finds Leto's ring during checking a bag.
Why did the Baron ask this question?
Answer
It's not really a question, he doesn't want an answer from the Duke, it's rhetorical.
Along with having him drugged and naked in the room, it's not just about ensuring he has no weapons, and cannot attack the Baron as they could have re-clothed him
The question is about intimidation and making the Duke anticipate his death, or worse. The Baron is just trying to enjoy the moment
Answered By - iandotkelly