But regulators have done that going on a century now, and it has held up in court. The FDA has long lists of definitions of what you can and can't call chocolate, milk, cheese, beef, etc.
Then they should do it in this instance as well. Until there's guidance, "autonomy" is just a word like any other and open to interpretation. In those instances, free speech should protect any company using the term and I say this as someone who 100% believes Tesla's advertising was deceptive.