The Baron wants to know how Arrakis fits into the Mentat's calculations about Salusa Secundus. The Emperor seems edgy about associations between the planets. The Baron needs to figure out what's what.
On the inside, Hawat thinks about how much he hates the Baron and about how destroying him will be a service to mankind.
On the outside, Hawat's all business. He tells the Baron why the Emperor was so eager to destroy House Atreides. It wasn't because Duke Leto was handsomer than him or more popular with the ladies. Rather, Leto had created a fighting force trained by Gurney Halleck and Duncan Idaho, the best of the best. The Emperor wanted that force destroyed while it was still small.
What does this have to do with Arrakis? Why, the Fremen of course.
The Baron tries to argue against the Fremen being such a great fighting force with even greater numbers, but Hawat is there to counter his arguments one at a time.
Hawat's estimate of Fremen living on Arrakis: 10 million. Hey, that number could begin with a B. Look on the bright side, Baron.
Hawat discusses Salusa Secundus next. His suspicion is that the planet is an inhospitable place, much like Arrakis. So the Sardaukar, like the Fremen, think that living in such a terrible place make them chosen people.
The Baron remembers Fenring's comment years ago, the comment about not making Arrakis a prison planet. Ding!
Hawat advises the Baron to let Rabban continue making life miserable for the Fremen. It'll only make the planet the Harkonnen equivalent of Salusa Secundus more quickly.
With that said, it's time to cut Rabban off from resources. The Baron and Hawat agree that when Rabban gets desperate, that will be the time to replace him with Feyd.
Hawat is dismissed. He thinks about Gurney's reports on some guy named Muad'Dib. Good to know he and Gurney keep in contact after all these years. He also gives up hope that Paul is still alive out there.