I don't know

Honestly like I don't know. My friend has been saying that he doesn't understand how I can find hookups and stuff and he can't because I hookup with a good amount of guys but just to be clear these are guys my age with protection and everything (I'm a junior in high school). He can't find anybody to hook up with at our school or neighboring schools because he's not the most charismatic or attractive person so he has turned to grindr to find hookups. He recently hooked up with somebody who was at least 27 with absolutely no protection.I am usually like a whatever floats your boat kinda guy but I've heard so many awful stories about teens getting taken advantage of by adults and I obviously know the dangers of unprotected sex ecspecially with a grindr hookup.I tried to talk to him and I was like hey this isn't ok but he was like "it's fine the guy showed me the papers so he doesn't have STDs" but I'm still worried about the fact that he is going to continue to find adults on grindr and hookup with them because he's a horny jealous moron.How do I stop him from doing this? I don't like him at all in fAct he annoys the fuck out of me but I want him to be safe and I would feel absolutely awful if he was taken advantage of or if he got sick. I just need advice on how to approach this situation. Thank you :)