Unconditioned sound changes do not exist. It is a most unfortunate label which has been around for a long time. It was about time we tried to get rid of it. There is always a cause behind the change - whether we know that cause or not is a different matter. But sounds just don't change all by themselves.
Any sound change is conditioned.
However, like the story of the Eskimo words for snow, this story about Whorf and Sapir is not factually correct. He also does not claim this connection between the ontology and the language to be a new idea. He presupposes it. That is a big difference, of course, because Whorf is often accused of claiming such a connection without giving any independent evidence about the ontology. But in fact he did not make any such claims, he merely assumed that there was such a connection because everybody around him assumed it also.