My (17M) friend thinks dumbell curls will make him shorter. How do I fix his brain?

my friend (17M, 5’6) is convinced that doing dumbbell curls (13-15 reps) will somehow damage his spine and stop him from growing taller. No matter how many times I tell him that lifting won’t stunt height, he refuses to believe me. I’ve tried different ways of explanation but he’s still acting like he is one bicep curl away from permanent 5’6 status.

Can someone give him some advice? Or maybe give me advice?