[GrantMoyer]

I don't think that can explain why they're only targeting certain sub-categories of porn, and it's also contradictory to the public statements by Valve:

> We were recently notified that certain games on Steam may violate the rules and standards set forth by our payment processors and their related card networks and banks

Individual games violating "rules and standards" doesn't really fit with prohibiting a category because of high rates of fraud.