I doubt that it has anything to do with social preferences of anyone internal to payment processors. They won't care.

Putting pressure on payment processors is a useful way to put pressure on any commercial service. The commercial service may operate in another country, but it needs the payment processor, and the payment processors don't want to be ejected from countries. The payment processor can be a lever for laws passed elsewhere.

Every payment processor on steam is a publicly traded company, not privately owned. So it wouldn’t really be up to any one individual’s moral preference about such things. Personal preference would only count in to it if one of the shareholders had enough shares to push the board around, but the only one where I could see that being the case would be PayPal from people like Theil and Andreessen. Like they’re both jack wads for other beliefs, but I wouldn’t exactly call them bible thumpers.

But that's only using like 2 minutes of the 2 hour return window

Wouldn’t the cost land at valve? I guess not with a chargeback, but no way someone creates and account everytime they buy a porn game.