It’s important to consider that a 9-year-old still is very young and has a lot of time left to develop creative writing skills. When I was 9-years old, I too had no interest whatsoever in creative writing, and I did not even read books. You have to encourage him step by step, gradually, to read first and then learn the creative writing skills. Adventure and mystery stories are generally preferred by that age group. You can try reading aloud if he doesn’t want to ready by himself. Also, don’t forget to be patient – a mindset doesn’t change quickly.