"Porn" is extremely broad. There's plenty of perfectly ethical porn around. Most major producers have pretty strong standards these days. It's not the same industry as it was 10 years ago.
But in this specific case they went after a porn game, not featuring real people. There's basically no real harm here. People occasionally argue that porn addiction is a problem, but that's mostly an addiction problem, which goes for most addictions. The thing addicted too isn't the problem, it's the very nature of being addicted that's causing the issue.
It's fine of course to dislike porn, but to effectively ban people from producing and consuming it is an entirely different matter. That does seem like a massive encroachment on individual rights to me.
I can think it's a messed up fantasy, but that doesn't mean it should immediately be banned by a payment processor.
Regardless, there are tons of studies showing that consuming this kind of porn actually helps prevent people from acting on these fantasies. The net result is likely less sexual abuse, not more. Because it's fantasy media, it likely is able to keep the fantasy a fantasy, it gives people an outlet.