That’s not the test of libel. Libel is a false written statement of fact that harms another person’s reputation. So you can libel a public figure, but only if you tell an outright lie about them that has the capacity to harm them in some way. For example, if King wrote a “nonfiction” biography claiming that Musk was a pedophile and that caused Musk’s stock prices to drop. But I don’t expect King or any other prominent writers to do that, because they aren’t idiots.
Or King could just write a novel where Musk gets impregnated by an evil clown or something, because that wouldn’t be presented as a statement of fact.
On the flipside Musk makes libelous claims against people all the time, from previously obscure figures like that random Jewish college student accused of being a Neo-Nazi plant to public figures like the woman Olympic wrestler Musk accused of being a man.
