Herbert wrote other books about the dangers of god-like AI, so it wasn't just an "I don't want this."

Dune is very much about systems of power and oppression, the obvious and less obvious forms they take, and the way they transcend and direct individuals. Even when the individuals are almost omnipotent - in theory.

The whole point of Dune is that these systems are human, but have an independent life of their own.

The narrative is about modes of human supremacy, and a jihad against AI isn't just some optional world building, it fits the narrative perfectly.