

What I see is Mastercard hiding behind their generic rules for processors and being fine with the processors taking unilateral action that could damage their brand.
Mastercard should demand they rescind the decision based on a flawed interpretation of their rules since the content IS NOT ILLEGAL where Steam provides it, or drop those processors entirely due to the brand damage their unilateral decision has caused. If Mastercard lets this sit, that signals that they agree with this decision, regardless of what they say, and they should be treated as such.
It is intentionally vague, because companies want to be able to weasel out of any and all accountability whenever possible.
But Mastercard isn’t off the hook either way even if we accept the rules as they are currently. Before this incident, Mastercard has been starting to censor adult content in general with rules changes. To the point where there was already a petition on the ACLU site about this exact type of censorship.
https://action.aclu.org/petition/mastercard-sex-work-work-end-your-unjust-policy
Mastercard is trying to weasel their way out of this particular instance because they didn’t directly have a hand in this video game situation, even though they clearly would agree with it based on other recent changes. They’re trying to play both sides by assuming that people didn’t know they were already doing these things.