The tools of oppression reading is backed directly by the books: "But that only permitted other men with machines to enslave them"

Is it also true that Fremen are canonically descendants of Zensunni practitioners, which is a mix of Zen and Sunni Islam

Many other restrict machines, and the dogma is encoded on a religious text called the Orange Catholic Bible. And, this might be a big jump but, some of the specific anti-machine quotes are similar to Matthew 12:31-32 IMO

Not a very deep justification. Probably the easiest thing to grasp for when thinking "how can I make this religious theme fit the narrative?".