Additional experience never hurts; on the contrary. The more work experience your son has, the easier it will be for him to achieve his goal. In high school, I decided I wanted to be a psychologist. I learned all about how to get a psychology degree and moved towards my goal. I took free classes from psychologists all over the world. Sometimes these classes took place offline, and I talked to interested people in this field. They told me a lot of interesting things about my future profession.