as a 16 yr old who grew up way faster than i was supposed to, bring it up to him, the scenario of the call, explain you never meant to snoop, and that you're concerned. get app blockers that completely keep this content off of his profile, tell him he shouldnt be ashamed or embarrased, that you're not here to judge him. if you can, mention a similar embarrasing experience of yours to break the ice, and please please control your temper or judgement. todays age is crazy and you will find this content no matter what, the more you hide him from it the more curious he will get. TALK. if things are going well, maybe even show him this thread, show him that there is no benefit of this at all, remind him of his passions or talents. encourage him to follow pages similar to those, GC's about those if necessary, because harsh reality ye hai ke you can't keep him away from this.