Our payment network follows standards based on the rule of law. Put simply, we allow all lawful purchases on our network. At the same time, we require merchants to have appropriate controls to ensure Mastercard cards cannot be used for unlawful purchases, including illegal adult content.

This sounds like trying to have their cake and eat it too. Steam wouldn’t have delisted that many games without a significant threat of retaliation from the payment processors for possibly publishing something that broke whatever criteria they count as an unlawful purchase.

One case I can think of is the ease of using a VPN to purchase content that is illegal where the person resides but legal elsewhere. Stopping purchases through VPNs would be one thing that valve has no realistic way to address, but if the payment processor insisted that they must avoid that kind of unlawful purchase or cut off all payments then I could see the end result of just removing all of the content.

Not saying it is that exact thing, just an example of something unrealistic that can still be described as a card being used for ‘unlawful purchases’.