Huh. I used to work in public libraries. We used to have a guy come in and look at porn on the computers. Nothing illegal, just generic stuff. He would open up a bunch of windows and then minimize them and leave. People would come along and maximize them and be faced with various porn sites. There was nothing we could do because we couldn’t censor people’s web surfing. We’d watch for him to leave and then discreetly go over and close all the windows he’d opened. So I’m calling some form of shenanigans here. Either he’s lying, or he was looking at something that was genuinely illegal.
Also, if he’s going to be a “preacher,” he should maybe think twice about posting this sort of thing on FB. So here again, I’m calling shenanigans.
It sounds to me like he’s (over)sharing as some sort of public-service. “Hey guys, in case you didn’t know, looking at porn will get you in trouble at the library. In case you weren’t sure about that kind of thing. Like, if you thought it was cool.”