What political sermon? Do you just mean the diversity of the cast and crew, or did you find something in the story itself that sent a more coherent political message than, "If your boss tells you to blow up the world, say no."
Well, he just introduces rudimentary technology to ancient humans and then stands back for thousands of years to watch it evolve.
He feels guilty that the chain of technological progress eventually leads to Hiroshima, but I don't think everybody would agree that it's his responsibility.