Your son sounds like he would do amazing with balancing pre-med studies and swimming D1. There’s no reason to discourage him from that, if he’s able to balance all of his high school responsibilities and has a passion for his sport! It would definitely be best for him to ask each individual coach about athletes on the pre-med track, like how feasible it is and how many players are currently pre-med. When I was speaking with D1 coaches (for rowing, but I assume swimming could be similar), some of them said they DELIBERATELY recruited pre-med athletes, as it shows their dedication and work ethic, as well as likely would bring the team’s average grades up. Best of luck!