A bit TMI but I grew up in a fundamentalist Christian household (aka super sexually repressed) in an abstinence only sex education state. My parents decided not to circumcise me or my brothers, my dad is apparently circumcised because neither of them told me how to clean down there or that foreskin even goes back. It was never once mentioned during any sex ed, anatomy, etc. classes in school. I had no idea that foreskin was even supposed to go back or that merely getting it wet in the shower wasn't good enough until I was 17. I had frequent irritation down there and I just thought that's how it was supposed to be. 4chan of all places taught me about phimosis and proper hygiene.

Not to excuse the guy in that posts' shitty behavior but for some people they are told literally nothing about their bodies or how to care for them and so long as it doesn't put you in the hospital, it's something you're unlikely to learn out in the wild. There may very well be people reading these posts that are learning how their genitals are supposed to function right now. I was one of them at one point

Dude just flying the ship around with the landing gear down.

Assuming that he knew that you need to retract the foreskin before penetration. Not something you really think about when it doesn't retract at all.