That's his parents job. Not yours.
This was actually what I said immediately. It doesn't do any good. Only causes gaslighting and arguments.
"yeah, but your his older cousin. you should be trying to get through to him".
I do care. It also doesn't feel that easy to approach somebody and immediately start chatting about a personal issue. He hasn't talked to me about it at all. If he wanted to come up to me and chat about his decision I would be perfectly fine. But I haven't gotten that impression.