Arrakis serves as a similar crucible, and the Emperor fears that the Baron could recruit from it a fighting force to rival his Sardaukar.
John Bagnell Bury noted "that The Emperor, suspicious though he was, probably believed that they were not morally guilty, but feared that they would be used as tools in future conspiracies.
The French Emperor, Napoleon III, feared that a powerful Germany would change the balance of power in Europe (the French opposition politician Adolphe Thiers had correctly observed that it had really been France who had been defeated at Königgrätz).
Arrakis serves as a similar crucible, and the Emperor fears that the Baron could recruit from it a fighting force to rival his Sardaukar, just as House Atreides had intended before their destruction.
Its nobles and merchants were becoming ambitious, and the Emperor feared these ambitions.
Paul said: "The Sardaukar on Arrakis are a measure of how much our beloved Emperor feared my father.
"You said the Emperor doesn't fear exposure."
Your Emperor fears that she knows his secret.
The Emperor so fears the mind, he would destroy a world.